Hi MikeL60,
This is much more a matter of a preference choice than a durability choice because the weak link of a mattress will generally be in the comfort layers not in the support system. Some people tend to prefer the familiarity or the overall feel and response of an innerspring mattress which is closer to the general type of mattress they are used to while some people prefer the feel and response of an all latex mattress. Since innersprings are closer to what most people are used to they can sometimes take a little less of an adjustment period than an all latex mattress although this certainly isn’t always the case and some people don’t seem to go through much if any adjustment period at all and take to an all latex mattress right away.
Some of the most knowledgeable people I know in the industry that could sleep on anything they wish to sleep on innerspring/latex hybrids (often a pocket coil) but of course others sleep on all latex or memory foam mattresses and when you are looking at high quality materials it really is a preference choice. There is also more about innerspring support cores vs latex support cores in post #28 here and in post #2 here and a few innerspring/latex hybrid sources that may be worth considering (outside of local options that may also be available) in post #2 here.
In theory a latex support core would tend to be more durable than an innerspring but in practice the difference is much less meaningful because the difference is in the deeper layers and assuming that either one would be a suitable choice in terms of PPP … once you are past about 10 years or so then the person on the mattress and the changes in their body and preferences can be the limiting factor in the useful life of a mattress as much or in some cases more than the mattress itself (although of course both types can last longer than 10 years for many people).
Phoenix