Hi Kooshball,
Comfort and firmness/softness is very subjective to each person and has many variables … especially with memory foam … and Serta doesn’t really provide any meaningful information about their mattresses outside of very generic information so they are not really suitable as a guideline except based on your own subjective perceptions of and comparisons with the mattress.
Post #2 here has more information about “matching” another mattress (or using it as a “quantifiable” guideline) and in this case the only way to use it would be as a very generic preference (such as I prefer firm mattresses which covers a very wide range of preferences and is subjective). I would suggest a more objective set of standards that you can use to assess all the mattresses that you test (such as rating each one on a scale of 1-5 for pressure relief, for support/alignment/ and for all the other preferences that are important to you). this way you have a way to assess different mattresses without the need to use one mattress as a “target” where there is no way to really know what the target even is or how it may compare to other mattresses outside of “real time” side by side comparisons which usually aren’t possible.
The better options or possibilities I’m aware of in the Raleigh area (always subject to your ability to find out meaningful specs about any mattresses you are interested in) are included in post #6 here.
Phoenix