Hi restless,
There are several ways to “duplicate” the feel and performance of another mattress.
The first of these is by equivalence which is possible if a manufacturer with enough experience and knowledge designs and builds a mattress that is reasonably close to the softness and support of another mattress that is known to them and this is confirmed with their own personal testing (and preferably the testing of a larger group of people like their customers as well). These may not have the exact same layering or even quality of materials (there are many ways to achieve the equivalent performance and/or feel in a mattress that has a different overall design) but they would be made in a way that they would be very similar in the experience of most people in terms of softness and support levels. Of course this depends on a retailer or manufacturer being familiar enough with another mattress you were trying to match that they could give you a meaningful comparison that would be accurate in most cases. Most manufacturers would only do this with mattresses that are widely available and popular enough to justify the time, effort, and even risk involved to compare their mattresses to another manufacturer and take the risk that their comparison wasn’t accurate enough and many of their customers didn’t agree with their comparison (which could lead to returns with customers that were using their comparison as their primary guideline)
The second is by feel which is a more subjective comparison and can be tested with side to side testing in real time. This needs to be very close together without any other mattresses “in between” because our subjective memories are not very long lasting. We have all for example experienced testing half a dozen mattresses in a store and not remembering exactly what the first one felt like or realizing that the “feel” of it seemed to change as we tested other mattresses which became new reference points. This also won’t tell you how they may compare a year down the road because lower quality materials can have a similar “showroom feel” to higher quality materials and lower density/quality will soften and degrade faster than higher quality materials. Feel is the most subjective of all the ways to match a mattress and is the result of how all the materials and components in the mattress interact together with each person and their individual perceptions.
Third is by quality of materials. This means that both mattresses use the same quality of materials and would have similar durability but the feel or the softness and support may be different. The quality/density of the foams is the most important part of durability but it has little to do with how a mattress feels.
Finally a mattress can match by design. This means that the type and quality of materials and the layering are all the same and in effect you are duplicating every layer and component in the mattress in terms of quality of materials and layering with foams made by a different manufacturer. Foams that may seem similar in some of their specs may have different properties in other ways or different firmness levels so this may not lead to a mattress that “feels” the same or has the same softness and support. For example two different memory foams of the same density may have very different temperature sensitivities, response rates and recovery times, firmness/softness levels and other properties that would create a different feel and performance between two seemingly very similar mattresses. You would need to know not only the density and thickness of each layer but would also need to know the firmness level and other properties of the foam and how they matched to the foam you were using to “duplicate” it.
The Sealy Memoryworks is not a popular enough mattress to be the “target” for another manufacturer and they don’t disclose the detailed specs of the materials they use anyway (the ones they provide are pretty much meaningless). This means that to duplicate this mattress the only way would be through your own comparisons based on your memory of its performance and subjective feel. If there is more than a few hours in between your testing of both or there are other mattresses “in between” … this is not likely to be very accurate.
This is highly unlikely and it’s much more reasonable to think it would be closer to half of this.
Tempurpedic is a little more open about the type of materials they use (HD = 7 lbs, Tempur material = 5.3 lbs, and ES = 4 lbs and their base layers are in the range of 2.2 lb polyfoam) but their foam density is only part of the story because they can make different types of memory foam with each density (for example they can make a softer or firmer version of the 5.3 lb memory foam) and even various types of fabrication (like convoluted airflow layers) can change the feel and performance of a mattress. (NOTE: Tempurpedic is no longer disclosing the density/quality of their materials and has changed the density of the base layers in at least some cases to 1.5 lb polyfoam.)
It is usually much more effective to evaluate each mattress you test against a common set of standards that are a little more objective. You could for example rate each mattress on a scale of 1 - 5 for each of the criteria that are most important to you which would give you a way to compare mattresses a little more objectively than just subjective “feel” alone. There is more about “mattress matching” in post #2 here and a more inclusive list with more information about many of the “needs and preferences” that may be part of each person’s “value equation” in post #46 here.
In general these needs and preferences will involve things you can know with testing (things like pressure relief, alignment, motion isolation, overall feel etc), others that you can only “predict” through knowing the materials that are in the mattress (ventilation and temperature control, durability, and how long a mattress may feel and perform the way it did in the showroom), along with the other factors that are important to each person’s “value equation” (such as the relative cost of two mattresses with similar materials and components, the knowledge, service, and options offered by the retailer before, and after the sale, natural vs synthetic materials, and any other less tangible options that may be important to each person).
One of the most frustrating ways to buy a mattress can be to use the more “subjective” memories of the “feel” of another mattress as a “target” where the materials aren’t known or where the layering is too complex to be effectively duplicated without the knowledge, experience, and guidance of a manufacturer that can “translate” one type of mattress into another with different layering and different variations of similar materials.
In your case … this rules out duplicating the memoryworks (except through side to side testing). The Tempurpedic line is so widespread and well known however that there are many manufacturers that will use them as reference points for their own mattresses.
You will find some of them in post #21 here where you will see that some of the manufacturers listed compare their mattresses to Tempurpedic or other well known brands in one or more ways to help their customers get a sense of how their mattresses will feel or perform or how it compares in terms of quality. If a close match is important then a good return policy can be a good indication of how confident a manufacturer is in their claims because few manufacturers would offer a low cost or free return if most customers were likely to return it.
Of course all of these may offer advantages that are better than the Tempurpedic which not as obvious in testing such as better breathability and temperature control (among others) besides the obvious advantage of having the same or better quality, and similar feel and performance at much better prices.
I’m not sure what the density is but it would surprise me if it was “lightweight”. Did you ask what the density was? I thought I had asked at one point but don’t have it in my notes. Latex makes a great base foam and is highly adaptable to different weights and sleeping positions (besides being durable) but of course as you mention it’s more expensive. The benefits would depend on the person and their body type, sleeping style, and their perceptions and preferences. ADDED: I thought I would find out for sure (and make notes this time :)) and Mark confirmed that they use anywhere from 1.8 lb in their lower end (good quality) all the way up to 2.8 lb polyfoam (exceptional quality) in their higher end. They don’t use anything less than 1.8 lb in any of their layers.
The most effective way to find this would be to call the Therapedic licensee that is the manufacturer for your area and ask them which retail outlet close to you may carry them.
Hope this helps.
Phoenix