Hi m00se.
Welcome to our Mattress Forum!
You’ve got the right ideas… you are correct that latex, in general, is the most durable of all the foam materials (latex foam, memory foam, polyfoam) regardless of whether it is Dunlop or Talalay or is made from natural rubber, synthetic rubber, or a blend of both.
“Sandwiching” the memory foam between two layers of latex certainly is a viable alternative that many people find comfortable. Speaking personally, I find a layer of latex on top of memory foam to be more comfortable than the other way around but that is my own personal opinion. Having Latex on top can add to the durability of a mattress compared to other materials. The deeper layers of a mattress also have an effect on mattress durability but to a lesser degree (a mattress will soften and break down from the top down) and will have more of an effect on performance and support/alignment. Whether or not you would like the feel of a latex on top … or … a latex topper on an existing memory foam mattress, of course, would ultimately come down to your own personal testing because while latex and memory foam can be equally “pressure relieving” they are very different materials with very different properties. There is more about some of the differences between memory foam and latex in post #2 here.
“Sleeping hot” along with the difficulty to reposition tend to be characteristic of memory foam that most people complain about. Latex, it is the most breathable of the foam materials and it is a great choice for temperature regulation. Generally, the layers that are closer to the top sleeping surface will have the greatest impact upon comfort/pressure relief and sleeping temperature (including your mattress pad, sheets, and linen). There is more about the many variables that can affect the sleeping temperature of a mattress or sleeping system in post #2 here.
Price as well is part of each person’s personal value equation and I certainly understand why you wouldn’t want to pay a premium for a Tempur bed, For the most part, they use good quality and durable materials but for most people they wouldn’t be in a particularly good value range compared to many other memory foam mattresses that use similar or better quality materials that would be just as durable. I personally would have a great deal of difficulty justifying a Tempurpedic purchase unless for some reason my needs and preferences were so unusual that there were no other alternatives available that would be just as suitable and “comfortable” in terms of PPP and used materials that were the same or better quality that would be just as durable as the Tempurpedic line … and this would be very unlikely.
While it is more unusual that you’d find a mattress that has a latex core and memory foam comfort layers…. FloBeds one of our expert members here used to have a hybrid and memory foam/latex and you could ask them a fee more specific questions about it. Depending of how much of the feel of the memory foam you’d like to bleed through the latex layer on top you can chose different layer thickness. Again personally I’d chose relatively thin layers of latex over relatively thin layers of memory foam because it can provide a more resilient and “movement friendly” surface feel and performance to the mattress while at the same time you can feel yourself more slowly sinking into the softer memory foam underneath. The latex would isolate the memory from your body heat to some extent so it would respond more slowly and/or be firmer than if you were sleeping directly on the memory foam. This can create a very interesting “feel” that some people like.
Allt the layers in a mattress work togheter and generally … 8" - 9" of latex is a good mattress thickness that can include the combination softer layers (or sometimes sections) for pressure relief and firmer layers for support that most people of average or even higher weights would need. In some cases … lighter weights or people that sleep in “flatter” sleeping positions, have slimmer less curvy body types, or who prefer a firmer mattress will do well with even 6". These are all good questions to ask the manufacturer or retailer of any mattress you are considering so they can discuss the differences between the different options they have available in terms that are more specific to the layers they use or options they provide. A 7to 8’ layering arrangement as you describe could work well provided that you select a suitable firmness/softness for your particular needs and preferences.
If you do decide to move forward with a 3" latex core , I’d be very interested in hearing what you found and how that works out for you.
Phoenix