First of all, this is an amazing site that is incredibly helpful to consumers purchasing a new mattress. Phoenix is quite the mattress consumer advocate; I wish you great financial success with this site.
Question I have not seen answered elsewhere: I am about to buy a Talalay king mattress with two separate firmness levels - one for wifey, one for me. With two stacks of different ILDs side-by-side does the center become âvalleyedâ and/or do the two stacks possibly rubbing together (again along middle of the bed âseamâ) cause any undue wear or breakdown on the sides of the Talalay over time?
Thanks!
Hi bbqBiker,
Thanks for the kind words 
There is a discussion of some of the pros and cons of split layering in post #2 here.
Most of this deals with the question of âwill I feel itâ though rather than your question about durability although they are related. In general there is an âedge effectâ with foam because the edge of a layer that is not glued doesnât have any material beside it on one side to moderate the compression directly under the body. While I donât have any links to âscientific evidenceâ that has tested this directly, because of the âstickinessâ of latex and also because most manufacturers will make sure that the ticking/quilting used (or alternatively a thin layer of foam over the split) is thick enough to even out the compression in the area of the split, any difference in durability is not likely to be significant enough to be relevant. I do know that in many cases ⌠the âtestingâ of different mattress designs or ticking/quilting combinations used by manufacturers that offer split layers before they offer the mattress to the public specifically includes the effect of the ticking/quilting or other layers on any split cores.
Phoenix