Hi MeDave,
There are more manufacturers looking to replace lower density polyfoams in their quilt panels with some of these newer generation “high performance polyfoams”. Some of these foams are also designed to mimic the feel of memory foam, albeit with faster response rates and less temperature sensitivity. And some of them are made more resilient and have comforts similar to latex. But of course, the overall feel of the mattress is dependent upon all of the materials within that particular mattress. And how “buoyant” or "dead’ of a surface comfort feel you desire would be a matter of personal preference.
While these higher density polyfoams do provide some unique levels of comfort, one of the best benefits is the extra longevity they can provide versus some of the less dense and lower quality polyfoam and memory foam materials that they sometimes replace.
Phoenix