Hi Restless_inNJ,
I think a lot of people are so used to all the “mattress hype” at the chain stores and with larger manufacturers that like you they are surprised at how much different it can be when you are dealing with real professionals and “mattress people” like Shovlin Mattress Factory who are more interested in helping you to make your best choices than “selling” you. In other words they put your best interests above their own (and understand that’s in their own best interests as well :))
There are many factors involved in the sleeping temperature of a mattress but on one of these is the type of foam that is used. Of the three major categories of foam (memory foam, polyfoam, and latex) … and almost all mattresses have some type of foam in the upper layers … latex is the most breathable and coolest over the course of the night. You can read more about the many factors involved in sleeping temperature in post #2 here and post #29 here.
It’s great when you you reach the point where you have eliminated the worst choices and only have good ones … and when you are at this point it will come down to your preferences and which parts of your personal value equation are most important to you. Good questions that are answered by knowledgeable people that can help “educate” your intuition along with all objective, subjective, and even intangible factors that are important to you can help you make the “best” choice when there are no longer any bad ones left 
Phoenix