Hi nhoblitt,
Yes … the thickness of individual layers and/or of the mattress as a whole can make a significant difference both in terms of how they feel and perform in terms of PPP and the options you have available to customize the mattress for your weight and body type. There is more about the effect of thickness of individual layers or a mattress in post #14 here and more about having more layers and options vs less in post #2 here.
I would make sure that you have a more detailed conversation on the phone with SleepEz as they know more about their mattresses and will give you better guidance about which of their different options have the best odds of working for your body type, sleeping positions, and personal preferences based on “averages” than anyone else (see mattress firmness/comfort levels in post #2 here).
Phoenix