Hi equestride,
The quality of a mattress in terms of durability and the useful life of the mattress depends on the type and quality/durability of the materials not so much on the design of the mattress or how many layers it has (see post #4 here for more about the variables that are involved in the durability and useful life of a mattress). There is also more information in post #3 here that may be helpful for those that are in higher weight ranges.
The suitability of a mattress in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) depends on the design of the mattress and the specific combination of materials and layers that are the best “match” for your body type, sleeping position, and individual preferences.
Latex comes in a wide range of firmness levels so one mattress that uses a specific combination of layer thicknesses may be very different from another one that uses the same thickness of materials in different firmness levels. For those that are more technically inclined there is more about some of the specs that are involved in mattress theory and design in post #2 here and there is more about what I call primary and secondary support and their relationship to pressure relief in post #4 here but in general terms this type of “theory” is much too complex for consumers that don’t have extensive knowledge about mattress design and materials and it’s more effective to go by your own personal testing or experience when it comes to deciding on a local mattress that is a good match for you in terms of PPP. If that’s not possible then the “next best” approach would be a more detailed conversation with an experienced and knowledgeable online manufacturer or retailer that puts your legitimate best interests and helping you choose a mattress that is the most suitable match for you above “making the sale” and where you are also comfortable with the options you have after a purchase just in case “theory” or the “averages” of other people don’t turn out as well as you hoped in “real life” (see mattress firmness/comfort levels in post #2 here).
Phoenix