Hi radiantchild,
Welcome … and I’m glad you found us.
The first place to start your research is the mattress shopping tutorial here which has all all the basic information, steps, and guidelines that you will need to make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
I would also be very cautious about using mattress reviews (good or bad) as a reliable source of mattress research or information and in many cases they can be much more misleading than helpful (see post #13 here).
Post #13 here and the posts it links to has more about the most important parts of the “value” of a mattress purchase that can help you make much more meaningful comparisons between mattresses.
Unfortunately you are the only one who can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved for anyone to be able to predict which mattress will be the best “match” for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) based on specs (either yours or a mattress) or “theory at a distance” (see mattress firmness/comfort levels in post #2 here).
Having said that … post #2 here has more about the different ways to choose a mattress (locally or online) that can help you reduce the risks involved with of each of them and help you make the most suitable choices.
I can’t see the specifics of the construction for this bedframe in the description but if it has at least 5 cross slats and a center beam with good support to the floor (at least one leg in queen and two in king) then it should be fine as long as you add a foundation that is suitable for the mattress you end up choosing. There is more about the types of support systems that are generally the most suitable for different types of mattresses in the foundation post here.
You can see my comments about the Old Bed Guy in this topic. You can also see some comments from one of the members here. I would believe what the evidence tells you 
You can see some comments and information about them in post #34 here (and the rest of the topic) and in this topic and a forum search on Charles P Rogers (you can just click the link) will bring up more comments and feedback about them as well.
Outside of making sure that a mattress is a good match for you in terms of PPP … a mattress is only as good as its construction and the quality of the materials inside it (regardless of the name of the manufacturer on the label) and if any of the Charles P Rogers are a good match for you in terms of PPP and you can confirm that there are no lower quality materials or “weak links” in the mattress you are considering (see this article and the quality guidelines it links to) and it compares well to any other mattress you are considering based on all the parts of your personal value equation that are most important to you then it would certainly be well worth considering. The same comments would apply to any other mattress you are considering as well.
Outside of the better online options that are linked in the tutorial post (in the optional online step) … if you let me know your city or zip code I’d also be happy to let you know about any of the better options or possibilities I’m aware of in your area.
I’m looking forward to finding out what you end up deciding … and of course any comments or questions you may have along the way that I can help with.
Phoenix