Hi w9oh,
The first place I would start your research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines that you will need to make the best possible purchase … and know how and why to avoid the worst ones (including all the major brands you were considering or any mattress that uses either lower quality or “unknown” quality materials inside it).
You can see my comments about Consumer reports in post #2 here and in this topic. As you can see I would consider them to be a unreliable source of guidance about purchasing a mattress.
This would be coming from some type of alignment issue. There is more about the most common causes of the “symptoms” that people generally experience on a mattress in post #2 here and while there are too many unknowns and variables involved to be able to “diagnose” or know for certain what is causing a specific symptom for any particular person … the most common cause of lower back pain is a mattress that is too soft.
What you need (and everyone needs) is a mattress that is a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). The most reliable way to predict this is to use the testing guidelines in the tutorial post. If you aren’t certain that you will sleep well and pain free on a mattress even with careful testing then the options you have after a purchase to exchange or return a mattress or to make changes to the layers inside it would become a more important part of the “value” of a mattress purchase. There is more about the different ways to choose a mattress and how to reduce the risks involved with each of them in post #2 here.
This will depend entirely on the specifics of the mattress you are referring to. There are different types of foam (latex foam, memory foam, and polyfoam) and each of them comes in a wide range of firmness levels so “foam mattresses” could range from being much too soft for you to much too firm for you depending on the specifics of the mattress. “Foam” is just a very generic description for any material that has “bubbles” inside it and it isn’t connected to the softness or firmness of a mattress.
There are many companies that have very good exchange and return policies and some like Costco are free (although this is the only positive thing about Costco and in most cases or for me at least wouldn’t be enough to overcome all the negatives involved in purchasing from them … see post #4 here) but I don’t keep a list of them in my head so this would just be part of what you would need to check with any of the local or online retailers or manufacturers you are considering (the tutorial post includes several links to the better online options I’m aware of in the optional online step). The importance of a good exchange or return policy is one of many factors that would be part of each person’s personal value equation. There is also more about the most important parts of the “value” of a mattress purchase in post #13 here that can help you make more meaningful comparisons between the “finalists” you are considering.
Phoenix