Hi Halifax,
Latex is a high quality and durable material and will be more durable than other foam types in general. Convoluted foam has less material in it so it will be less durable than the same material in a non convoluted version but the Latex Supreme is also a two sided mattress so this would increase it’s durability.
All mattresses will soften and break down from the top down so it’s usually the top comfort layers that are the weak link of a mattress and the most important layers to make sure that the materials are good quality and durable. I personally wouldn’t have a concern with a convoluted latex layer that wasn’t too thick in terms of durability and this would be even more true for a two sided mattress.
Having said that … durability and suitability are completely different subjects. If a mattress isn’t suitable in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) then no matter how durable it is if it isn’t suitable for you to sleep on then you would just have a long lasting mattress that you can’t sleep on.
A topper can be a great idea on a mattress that is too firm and needs some extra pressure relief and it will also improve the durability of the layers below it but it can be as difficult choosing a suitable topper as it is choosing a mattress. 3" would be a very large difference and you would need to have good confidence that a topper that thick in the ILD you choose would work well with the mattress you are using it on and would be suitable for you in terms of keeping you in good alignment in all your sleeping positions. The thickness and firmness of a topper and how it interacts with the body type and sleeping style of the person along with the mattress underneath it are all important considerations in choosing a topper (or a mattress). There are some topper guidelines in post #2 here that can help to choose the most suitable topper based on your real life experience on a mattress (and I would always sleep on a mattress first before choosing a topper so you can use your experience as a guideline) but as you can see 3" would be a “fair bit to a lot” in terms of extra softness. I would also keep in mind that a 32 ILD core is a little on the soft side for a base support layer for some people so this may also indicate the need for a thinner topper. No matter what you add on top of a mattress, if you need a firmer base layer for better support or alignment then a topper won’t help.
In general it’s less “risky” to choose a mattress or a mattress/topper combination that you can test in person but without this the best way I know to make a topper choice is using the guidelines. It’s also less risky to choose a mattress that is a little too firm than too soft because even with the difficulty of choosing a topper … it’s less risky than choosing a mattress that is either too soft in the support layers or too thick/soft in the comfort layers. You can always add softness to a mattress with a topper but you can’t make a mattress firmer without replacing either the support layers or the comfort layers (depending on which layer(s) are too soft and need adjusting).
So if your testing indicates the Latex Supreme is too soft for you either in terms of primary support (the firmness of the support layers which “stops” the heavier pelvis from sinking down too far) or secondary support (the thickness and firmness/softness of the comfort layers which provides pressure relief and fills in the recessed gaps in the sleeping profile to help maintain alignment of the spine) or a combination of both (because all the layers affect each other and interact together) then I would certainly choose the basic model even with the added difficulty of choosing a topper.
Phoenix