Your questions lead to an answer that may be more complex than most and I thought I’d reply in much more detail than normal so I could use the reply as a reference post for others as well. This post will deal with “feel” and the difficulties of trying to duplicate another mattress which is being used as a subjective “standard” and the next post will deal with your other questions.
Like chemistry where different combinations and amounts or variants of very similar chemicals or the addition of a single catalyst or reagent can result in very different reactions and outcomes … variations of different materials (like the many different types of memory foam, different layer thicknesses or various extra or missing layers in one mattress vs another) can result in very different performance characteristics and feels between two mattresses. This is made even more complex by the infinite variations of sleeping positions, body shape, and weight distributions between different people … all of which will interact with the same mattress very differently. For example … a mattress with a certain material that is 5" deep may have little effect for someone that wasn’t heavy enough to sink down enough to feel it but could have a significant effect for someone that was much heavier. To further complicate things … this effect may be noticeable in one position (on the side for example) with larger body prominences (hips and shoulders and others) that were exposed to the mattress surface than they would be in a “flatter” position (say on the back) that didn’t have the same degree of bony prominences that were interfacing with the mattress.
All of this is to say that the only way to “duplicate” a specific mattress is to use the same foam variants in the same layering scheme with the same mattress cover. While there are many combinations of materials and construction that can lead to similar degrees of pressure relief and alignment (what someone “needs” in a mattress) … they will have different properties such as motion isolation, speed of response, breathability, resilience, motion restriction, depth of cradle, surface feel and many other different characteristics (what someone prefers in a mattress that is a significant part of its “feel”). Post #9 here for example includes some of the many different properties that can be found in the many different types of memory foam and post #7 here has more about the differences in “feel” between Dunlop and Talalay latex.
Because of this … it’s usually important to set specific characteristics as your target rather than a certain mattress because the “feel” of a mattress is a more subjective description which has many different components and can be very different for different people (depending on how their unique body weight/shape, sleeping habits, and perceptions interact with a certain mattress design).
All of this is made more difficult by the fact that the manufacturers of the mattresses you are looking at may not fully describe the materials in the mattress (or the differences may be more subjective) so it can be very difficult to “translate” one material or mattress design into another in any objective way.
There are probably hundreds of mattresses that would “match” the pressure relief and alignment “needs” you have and be close in “feel” to what you preferred and it’s likely that most retailers or manufacturers with a fairly wide range of choices would have a model that meets your criteria even though it may “feel” differently.
Just as important though is how long will a particular mattress continue to perform and “feel” similar to the way it did in a showroom. This is something you can’t feel with your testing and relies on having some knowledge of the durability and quality of the materials in a mattress. More durable and higher quality materials are more expensive and are generally found in mattresses in a higher budget range. This is where the major manufacturers completely fail in most cases because they won’t provide this information so that consumers can make meaningful comparisons between mattresses in terms of “value” and durability. Of course this is by design because if a certain “feel” can be accomplished using various combinations of lower cost and quality materials … then selling a mattress at a price that should include more durable materials leads to higher profit margins and there is no way for a consumer that doesn’t know what to look for to know any better.
This is compounded by salespeople who are trained to sell mattresses based on marketing stories or “showroom feel” which is a subjective perception that varies from person to person and that can be easily managed in a showroom. For example the order that a consumer tries different mattresses will lead to completely different perceptions and opinions of each one than if the same mattresses are tried in a different order. Perceptions of “feel” are also highly influenced by what a consumer is told about a mattress as well. Marketing stories in other words can have an effect on what someone feels on a mattress.
More challenging yet is the difficulty of applying objective standards to subjective perceptions and that we don’t have an accurate memory for subjective “feel” for very long. Almost everyone has experienced lying on many different mattresses in a store and not clearly remembering how the first one “felt” or trying a mattress in the morning and then testing other mattresses at other stores and then returning to discover that the mattress they were using as a target now feels very different from what they remember later in the afternoon.
So the goal is to as much as possible to identify different qualities that are important and test for and measure each mattress against these specific qualities rather than comparing the feel of different mattresses against each other.
These specific qualities are first of all your needs (see the basic functions of a mattress) which are Comfort/Pressure relief and Support/Alignment when you are fully relaxed with no muscle tension (like when you are asleep) in all your sleeping positions. This means specific testing on each “candidate” for at least 15 minutes fully relaxed. Each person has a range of tolerance where their pressure relief and support needs are met. This can vary from “just barely enough” to “lots of room to spare” depending on where you are in the range between “princess and the pea” to “I can sleep on anything”. In general … it’s wise to remember that many materials will either soften (foam) or compress and become firmer (fibers) over time so if someone’s needs for either pressure relief or alignment are “just barely in their range” … the initial changes in some materials, especially foam softening, during the first 90 days or so of use (which is followed by more gradual changes) may put them over the line to “not enough”. This is where knowledge of the initial changes that will happen in a material and the ongoing changes that follow can be important.
Beyond your basic needs everything else is preferences. These include …
Motion isolation: This needs to be tested with both people on a mattress if it’s for a couple and with normal sleeping movements in the testing including getting on and off the mattress. Each person or couple may have a very different sensitivity to this.
Motion restriction: Some materials (like memory foam) are less resilient and slower responding to changing sleeping profiles which to different degrees will restrict the natural movement and changing of position that occurs during sleep. Others are more resilient and instant responding and allow or assist movement more. It’s important that natural and healthy movement and changes of position (which varies from person to person) during sleep is not restricted beyond the preferences or tolerance of each person. Because sex also happens on a mattress … this is also an important consideration for most couples and motion restricting mattresses are less “sex friendly” for the majority of people (see post #2 here about sex and memory foam).
Temperature regulation: This is perhaps one of the most important of the “preferences”. There are many factors involved in the sleeping temperature of a mattress and many of them are dealt with in post #2 here. Some of these can be noticed or felt in testing but many of these involve some knowledge of the materials and components in a mattress and the odds that a specific combination will lead to heat issues for a particular person. Heat and the ability of the mattress components and materials to ventilate and breathe are directly connected and there are also various types of either “heat conductive” materials or “phase change” materials that can also provide incremental improvements in regulating temperature although control of humidity and ventilation is the most important of these. The three main temperature regulating technologies are described at the end of post #4 here.
Depth of cradle: Some people prefer to be more “in” their mattress and some people prefer to sleep more “on” their mattress. Softer thicker materials will be more “in” while thinner firmer materials may be more “on”. Slow response materials will tend to be more “in” and faster response materials will also tend towards “on”. How each material compresses differently will affect this. Regardless of the depth of the pressure relieving cradle or whether you are more “in” or “on” the mattress … it’s always important to make sure that you are sinking in evenly so that you are in good alignment in all your sleeping positions.
Overall springiness or liveliness: This is connected to a property called hysteresis which is the amount of energy that is absorbed vs resilience which is the energy of movement that is returned by a mattress. This is also connected to motion isolation and motion restriction and to heat (energy absorbing materials tend to be warmer because mechanical energy is changed to heat when it is absorbed) and is also a significant part of the “feel”. Some people prefer a more springy, resilient overall response in a mattress and others prefer a more dead or energy absorbing overall response in a mattress. This can be tested by moving around on the mattress with either larger or smaller movements.
Hand feel or surface resilience and softness: This is the surface feel of a mattress with shallow compression and has an effect on how people perceive a mattress. Thin soft quilting layers can modify the way a mattress distributes weight and pressure. For many people who are more sensitive to and don’t like more “even” pressure distribution in some areas of their body (such as the small of the back or waist), or who perceive denser memory foams as too firm (because they take longer to mold to changing body profiles with movement) or just because they like a soft surface feel … this can also play a role in subjective or even objective comfort.
These are many of the “preferences” that may be very different for different people and while they may not be “essential” in terms of needs … they can also play an important role in overall comfort and long term satisfaction with a mattress.
Finally there are issues of durability. This involves identifying any “weak links” in a mattress and knowing the qualities and relative durability of different materials (see post #4 here). Without “full disclosure” of the materials in a mattress (including foam density in the case of polyfoam and memory foam and knowing the type and blend of any latex that is in the mattress) … knowing how long a mattress is likely to maintain the properties that led to your purchase are impossible to know. The only exception to this is around an inch or so of materials in the upper layers of a mattress (usually in the quilting) which is already soft and is precompressed with the quilting processso that further softening will have less effect on the mattress’ performance and it’s durability. Of course knowing the type of quilting materials is important so you can tell whether they will compress (fibers) or soften (foam).
More durable materials are more expensive (and higher performance materials are also more expensive even if they are the same in terms of density/durability) and while the initial needs and preferences of different people can be easily met with lower cost and less durable materials … the performance and feel of the mattress will change much more quickly when they are used. This is one of the biggest reasons why knowing the “specs” of the materials and layers in a mattress … particularly of the foams in the upper layers … are so important. Without this information you only know the type of material and every material includes low cost/quality versions that are less durable and higher cost/quality versions that are more durable. The overall durability of a mattress and the durability and quality of the individual layers in it should be one of the most important reasons for a higher budget. Heavier people or people who are more “active” or tend to be harder on a mattress will need more durable materials than lighter people or less active people to have a similar useable lifespan in a mattress. There is more about the factors that are involved in durability in post #4 here.
So all of this is about the “targets” that should be used as more objective standards that each mattress you consider can be measured against. If a consumer has a more specific picture of what they need and prefer and these qualities can be more accurately separated and described … then each mattress can be “measured” against a more objective standard rather than more subjective perceptions.
Part two (two down in post #4) will talk more about how to find the better outlets and manufacturers that already have a combination of the knowledge, skill, experience, and integrity to better educate their customers about their mattresses and make or sell mattresses that have the quality and value that can dramatically increase your odds of making better choices without having to learn all the technical details that can take a great deal of time and effort (and cause headaches :)) to sort through all the conflicting material and mattress information and trying to decide what is accurate, can be believed, and what is just marketing, self promotion, or attempts to sell more expensive mattresses with lower quality materials and increase profit margins.
In other words … it’s about how to simplify all of this and buy a mattress with good quality and value that will meet your long term needs and preferences without having to learn all the complex information (like this post) that can sometimes be overwhelming.