Hi smashing,
I know you’ve seen this but for the sake of others who may be reading this thread the Spokane list is in post #2 here.
The weak link of a mattress is in the upper layers so the materials that are used there are the most important part of durability. If two mattresses have the same type, firmness, and thickness of latex on top then they would be very close to each other in durability because most higher quality support components will also be durable (whether it is an innerspring, latex, or polyfam).
I’m not sure what you mean by “mixed” latex comfort layers (mixed with what material?).
There are other factors involved in durability as well (see post #2 here) including the relative softness/firmness of the layers (softer materials are less durable than firmer layers of the same material). In some case if the comfort layers are thinner, then the support layers would come into play more as well (they would be repeatedly compressed more) and then their durability would also be a bigger factor.
So in the example you gave … if the comfort layers were the same type of latex and the same thickness and softness (and not really thin) then the innerspring version and the polyfoam version (assuming both were good quality) would be roughly equal although they would feel and perform differently (depending on the type of innerspring and the type of polyfoam).
The same would hold true for a latex support core. While good quality firm latex would be more durable than either an innerspring or polyfoam (if you were sleeping on it directly) … the “weakest link” would still be in the upper layers so their relative durability would be comparable (with the same type and thickness and firmness comfort layers) although again the feel and performance of the different versions would be different.
The Snowmass (and the Aspen) both use blended Talalay latex. I have often mentioned them in many places around the forum as being good quality and value. A search on “Snowmass” (you can just click this) will bring up many posts that mention it.
In my experience … NW Bedding makes good quality mattresses and they are “good people” but their value is not in the “best value” range. In this case the Snowmass would probably be better value given the greater latex content but the “value” of a mattress is not just in it’s cost and how it felt and performed in terms of PPP (Pressure relief, Posture and alignment, and personal preferences) and in terms of all the other factors that are involved in “value” (see post #46 here) would also be important IMO. The Snowmass would be starting with a “value advantage” though if all the other factors are equal. How much the polyfoam base came into play would depend on the thickness of the latex over it.
Probably not, although they may contain some components or materials that are “extra” (such as wool or better ticking or other materials besides just the latex). While they are better value than many major brands … they do tend to be more than other smaller manufacturers.
I also think highly of them based on my conversations with Paul. I know they make a mattress with a 6" Dunlop latex core with a Talalay comfort layer that may well be worth looking at.
Phoenix