Hi FAUguy,
In the same way that your experience on the Rhapsody wouldn’t be an indication of how you will feel on every memory foam mattress … it’s unlikely that your experience on a single latex mattress would exclude a whole category of material. It’s more likely that the specific combinations you’ve tried aren’t suitable for you rather than the latex itself.
There is some information in post #2 here about the different types of “symptoms” that people may experience on a mattress and some of the most likely reasons for them.
I’m not sure of the specific symptoms you are feeling or where you are feeling them or which sleeping positions they tend to happen but the most common (although not the only) cause of back pain on a mattress is that the mattress is too soft. Pressure points also aren’t nearly as likely for back sleepers with a soft layer on top and the odds are higher (although not certain) that they are coming from alignment issues. Your couch would also almost certainly be firmer than your mattress.
Phoenix