Hi Cajen9669,
You’re right except that it’s not only rarely but I never make specific suggestions or recommendations for either a mattress, manufacturers/retailers, or materials because the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components would be the best “match” for you in terms of “comfort” or PPP or how a mattress will “feel” to you based on specs (either yours or a mattress) or “theory at a distance” that can possibly be more accurate than your own careful testing (using the testing guidelines in step 4 of the tutorial) or your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
This actually has nothing to do with whether a manufacturer or retailer is a member of the site or not or whether providing this type of advice would be a “conflict” … but because it’s just not possible for anyone to provide these types or suggestions or recommendations for someone else outside of a manufacturer or retailer themselves that is providing information about their own mattresses based on their knowledge and experience with hundreds or thousands of customers and even then they can really only compare their own mattresses or mattresses that they are familiar with based on “averages”. In other words no matter how knowledgeable I may be or how much I may know about mattresses or mattress materials … I wouldn’t be the most reliable source of this type of guidance or suggestions and I would be very skeptical about anyone or any website that claims that they can provide these types of suggestions or recommendations outside of the retailers or manufacturers themselves.
I can certainly help you to narrow down your options, help you focus on better quality/value choices that are available to you either locally or online, help you identify any lower quality materials or weak links in a mattress you may be considering, act as a fact check, answer any specific questions you may have along the way that I am able to help with, and help with “how” to choose but only you can decide which specific mattress is the best match for you based on all the parts of your personal value equation that are most important to you.
Unfortunately there is no way to quantify the useful life or a mattress or predict exactly when you will decide to replace it (because this is the only real measure of durability that counts) because it depends as much on where you are inside the comfort/support range that is suitable for you and your own sensitivity to changes in a mattress as it does on the mattress itself. If for example a mattress is close to being too soft for you and is on the edge of the comfort/support range that is suitable for you then even a very small amount of foam softening can take you outside the range that would be suitable for you and you may decide to replace the mattress much more quickly because you are no longer sleeping well on it even though the same mattress could last for considerably longer for someone else even if superficially they appear to be similar to you in terms of their body type and sleeping style (see post #2 here). There is also more about the many variables that can affect the durability and useful life of a mattress relative to different people in post #4 here.
Having said that … if a mattress uses materials that would be more suitable for those that are in a little lower weight range … and the mattress is well inside the comfort/support range that is suitable for you … and if you are closer to the “I can sleep on anything” end of the range than the “princess and the pea” end of the range … and since you are only on the lower end of the weight range where I would be more cautious about using thicker layers of 4 lb memory foam … then it would probably be realistic to expect somewhere in the range of “more than half” of the normal 7 - 10 year lifespan that would be reasonable to expect from a mattress that meets the minimum criteria that I would normally suggest for more average weight ranges. I would always keep in mind though that this is only just a guess because of all the variables involved and for some people it could be less and for some it could be more because nobody has a crystal ball that can predict when you will decide to replace a mattress because you are no longer sleeping “well enough” on it.
There is a link to a list of the better online memory foam options I’m aware of in the tutorial post (in the optional online step) that would be well worth looking through and while I don’t know all the foam densities in all the mattresses there off the top of my head … I know that the Christeli Madeline here does use 5.3 lb memory foam but it isn’t gel memory foam if that’s important to you although gel memory foams may not sleep cooler over the complete course of the night than some of the more breathable non gel memory foams that are available in the market. there is more about gel foams in post #2 here.
In general terms latex is certainly a more durable material than memory foam (even in higher density ranges) but I’m not sure why you would be saying “UGH” about latex/innerspring mattresses because the choice between different combinations of materials or types of mattresses is always a preference or budget choice rather than a “better/worse” choice (see this article). There is also more about the differences between memory foam and latex in post #2 here. Some of the most knowledgeable people I know in the industry that could sleep on any type of mattress they wished to sleep on latex/spring hybrids (see post #13 here).
It’s certainly possible that memory foam mattresses may be your personal preference in which case they would be “best for you” but outside of preference or budget issues one type or category of mattress isn’t inherently any “better” than any other.
Phoenix