Hi jk,
IMO … any differences in durability between them wouldn’t be possible to predict to the level of specificity you are hoping for except in hindsight (and even that would be mostly subjective) and wouldn’t be a significant part of a meaningful “value” comparison between them. Any small “theoretical” differences between them in terms of durability wouldn’t be nearly as significant as the other parts of a meaningful comparison that are much more important and are possible to know. Just for the sake or argument and to make the point … lets say that one of them ends up being 5% more durable than the other (and this isn’t possible to know when two mattresses are so close in materials and design so its just a hypothetical example) … but that you would sleep just a “little” better on the other one for slightly less time. This means that one mattress may last you for ten years and the other one may last you 6 months less (not factoring in that when you decide to replace a mattress also isn’t that exact). I would personally rather sleep better over the course of 9 1/2 years than have a mattress that was less suitable for me and that I didn’t sleep as well for that same 9 1/2 years just for the sake of being able to keep it for 6 months longer. The same concept would apply to very similar mattresses where the price differences were relatively small.
As you probably also read in the post about the variables involved in durability (see here in particular) … how long a mattress will maintain suitable comfort and support for one person can be very different from someone else.
Once you have eliminated all the worst choices and are down to finalists between “good and good” (which you would be if these were your two finalists) … then a final choice will really come down to “best judgement” based on all the objective, subjective, and intangible parts of your personal value equation that are most important to you because neither one of them would be a “mistake” … especially compared to the majority of the mattresses in the mainstream market.
I wouldn’t foresee any long term durability issues with either one of them and and both are likely to last for a decade or longer but even if both mattresses were still in relatively good condition after a decade (which would be more than reasonable to assume in both cases), the limiting factor in terms of the useful life of a mattress and when you decide to replace it after a decade is more likely to be changes in the needs and preferences of the person sleeping on it as they age and their body changes than the durability of the materials themselves.
Phoenix