Hi blackbird,
Just to clarify your comments for the sake of accuracy … this is not a quality issue as much as a suitability issue. While the materials in your mattress are very high quality for the budget range of your mattress … I would agree that higher weights will often do better with higher density or firmer foams than more average weight ranges or lighter (see the memory foam guidelines here and the information here for some examples of some of the guidelines that are linked in the tutorial post) although this can vary widely from person to person because weight distribution, different body types, and different variations in sleeping positions and style can also make a significant difference.
Phoenix