Hi COUSINROSE,
I switched your post to a new thread of your own to keep the topic separate from the foundation thread.
The first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines you will need to make the best possible choices.
Outside of testing a mattress for suitability in terms of PPP … a mattress is only as good as its construction and the quality of the materials and components inside it. If you can find out the specific details of all the layers and components of the Charles P Rogers Powercore mattress you are considering (or link to a page that includes them) I’d be happy to make some comments about them. Without this information there is no way to assess the quality of their mattresses or identify any weak links they may have.
Plushbeds makes some high quality latex and latex hybrid mattresses and are transparent about the materials they use but I would make sure you compare them to some of the other online latex options you have available to you that use the same quality materials and are sold by some of the members of this site (they are listed in post #21 here which is also linked in the tutorial post) so you can decide which is the best “match” for your personal value equation.
There may also be some good options available to you locally that you can test in person and if you let me know your city or zip code I’d be happy to let you know of any of the better options or possibilities I’m aware of in your area.
Phoenix