Hi BGFalcon,
Just in case you wish to do some additional local research or testing … the better options and possibilities I’m aware of in the Cleveland area are listed in post #2 here.
The ILD of differerent types of foam aren’t comparable and there are also other specifications that affect how firm a material feels besides just ILD alone (see post #4 here) so it’s not really possible to make a meaningful comparison between polyfoam IFD and latex ILD (see post #6 here).
There is more about the different ways that one mattress can “match” another one in post #9 here but I would keep in mind that even seemingly small differences between two mattresses in the type of materials, the thickness and firmness of each layer, and the type of cover can make a surprising difference on the overall feel and performance of a mattress and on how two mattresses compare.
If you can’t test a mattress in person then then the most effective approach would be a more detailed conversation with a knowledgeable manufacturer that can help “talk you through” the options they have available that have the best chance of success based on the “averages” of their customers that are similar to you. If you aren’t confident that a specific design would be a good match for you in terms of PPP then I would seriously consider making the return or exchange options that are available to you and any costs involved a much more important part of your personal value equation to lower the risk of an online purchase that doesn’t turn out to be as suitable a match for you as you hoped for.
Phoenix