Hi hookalot,
The Serta Pure Response you are mentioning are good quality mattresses but the specs you are mentioning aren’t quite right. The bottom core has 6" of Talalay and 2" of firm polyfoam on the bottom.
These are among Serta’s better efforts IMO and in some cases can even have better than average value (depending on the retailer you are buying from).
I suspect you are in Utah where these mattresses are most often sold so I would do some price comparing if that’s the case.
For example … these would be OK value (but certainly not good) but the value here would be much better.
I would also do some careful testing because the Supreme in particular has very low (soft) ILD’s.
There are some other latex choices in the Salt Lake City area that I would also include in my research (again if that’s where you are).
Phoenix