Hi trconsumer,
As you probably know from your reading here Arizona Premium is one of the manufacturing members of the site which means I think very highly of them and that they compete well with the best in the industry in terms of their quality, value, service and transparency. You are certainly looking in a good direction.
I would keep in mind that firmess is very subjective and what feels “too firm” for one person or even a group of people can feel “too soft” for someone else. The only way to know how suitable a mattress or any combination of materials will be for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) is based on your own testing or sleeping experience which may be very different from someone else. When you can’t test a mattress in person … then the most effective approach would be a combination of testing mattresses that use similar materials and designs locally (if there are any available) in combination with more detailed conversations on the phone with an online manufacturer or retailer you are considering. The more information you can provide them your body type, sleeping positions, personal preferences, and mattresses you have done well with in your testing or in the past the more you can help them help you make the best possible choices (see mattress firmness/comfort levels in post #2 here). They will have more knowledge and experience in helping their customers to make the best possible choices out of the options they have available and based on the “averages” of other customers that may be similar to you than anyone else.
Phoenix