Hi thecountofzero,
You can read more about some of the challenges involved in trying to “duplicate” another mattress and the difference that smaller seemingly insignificant differences can make in post #9 here. You can also read more about some of the specifications that can make a difference in how a mattress feels and performs in post #2 here. In general you would be much better off assessing every mattress you test to a common set of criteria than using a more subjective “target” like the feel or performance of a specific mattress as your guideline.
If you were able to find out the exact type of materials and all the quality specs AND the comfort specs of a mattress (such as ILD) and the cover and quilting (including the quilting pattern) were the same then it would be a close approximation but in most cases, except with very simple designs, you either won’t be able to find the information you would need in enough detail or you won’t have access to exactly the same layers and components to be able to duplicate another mattress. The specs you listed don’t include all the “comfort specs” you would need or some of the other specs (such as resilience and compression modulus or even the quilting pattern of the cover/quilting) that you would need to match the different layers and that can make a difference in how a mattress feels and performs.
In terms of quality and durability and the risk of foam softening and the more rapid loss of comfort and support yes. In terms of how it affects PPP or the “showroom feel” of the mattress no, because you can test for this in a showroom but of course the showroom feel won’t last if a mattress uses lower quality materials … especially in the comfort layers. In terms of the “value” of using low cost materials in a premium priced mattress instead of using higher quality more durable materials or the “value” of the mattress as a whole it would depend on each person’s personal value equation and how it compared to other mattresses you were considering based on the criteria that were most important to you. My main caution or concern would be based on durability and the “value” or wisdom of using low cost less durable materials in the comfort layers of a mattress in this price range.
Phoenix