Hi adamjaybernstein,
The first place I would begin with any mattress search is post #1 here. It includes all the basic information steps and guidelines that will help you make the best possible choices. One of the first overviews that are suggested reading there is here which talks about the two basic functions of every mattress which are pressure relief (comfort) and alignment (support).
Support is also connected to the firmness of a foam, not the density of a foam. Firmness is what “stops” the heavier parts of the body from sinking in too far and any density of polyfoam can be made in any firmness level. Density is connected to the durability of a foam and how long it keeps its firmness level. Post #4 here has more about the different factors involved in durability and post #6 here from earlier today includes more information about the Dreamfoambase density so you can make a more informed decision without mixing up apples (density and durability) and oranges (firmness and support).
Phoenix