Hi FAUguy,
I’m glad to see that they finally removed the lower quality materials in their previous generations and replaced them with a higher quality/density and more durable version of polyfoam which would no longer be a potential “weak link” in their mattress in terms of durability and the useful life of their mattress.
With the change in foam quality/density of their 5th generation then there would be no cause for concern with the durability or useful life of their mattresses and if you have done some careful testing to confirm that the mattress you are considering is a good match for you in terms of PPP then you would have covered two of the three most important parts of the “value” of a mattress purchase that are listed in post #13 here (suitability and durability).
Of course I would still make some very careful “value” comparisons between the Prana and other mattresses or the other “finalists” you are considering that use similar types, thicknesses, and quality of materials based on all the parts of your personal value equation that are most important to you including the price and the options you have available both before and after a purchase to customize the mattress or exchange the mattress or individual layers if the choice you make doesn’t turn out as well as you hoped for. I would always be very cautious once you are above about $3000 (queen size mattress only) or the equivalent in a king size (about $3500 - $4000 mattress only) so that you have a compelling reason to buy a mattress in this price range that makes sense to you and that would make the additional cost vs the other options you have available “worth it” to you.
Savvy Rest doesn’t provide the ILD’s for their layers but the general range is in post #2 here. The ILD range for SleepEZ is near the bottom of this page.
Softness/firmness is very subjective and relative to each person and a mattress that feels soft for one person may feel firm for another depending on how their body type, weight distribution, and sleeping style interacts with all the layers and components of a mattress and their own individual sensitivity. There are also different types of softness/firmness that some people may be more or less sensitive to (see post #15 here). The comfort and transition layers in the PLB Beautiful would be softer overall than the Savvy Rest but for some people the softer bottom layer (in spite of the alignment risks involved) may “translate” into an “all soft” Savvy rest feeling softer to them even though it may not feel softer for other people.
Assembling a component mattress such as SleepEZ or Savvy Rest is generally a fairly simple process but it would be much easier with two people. The foundation is easy for one person to put together and is made specifically for latex mattresses and would certainly be suitable and strong enough for an all latex mattress and it wouldn’t be a “weak link” in your sleeping system.
Phoenix