Number 1 mistake is valuing pressure relief/comfort over support. This gets back to PPP and Pressure Relief over Posture.
I think a lot of back sleeper buyers get too amazed by comfort over support. And when they do that……they usually end up with back pain because hips sink down too far. Advice: dont let your hips sink down too far and dont let you sacrum bend at an acute angle.
This is why Purple and Tempurpedic sell so well…great pressire relief, but support can be lacking for back sleepers and then they have lower back pain. Observe comfort and support, not just comfort. Carefully observe how much your hips sink down. It is sort of hard to do…
I tried Purple 4. It felt great in the store. It felt so great that I glossed over lower back support. I bought it….took it home. After the 2nd night, lower back pain every night. I had to return it. The Purple mattress may work for some.
Get a comfortable mattress for sure!!! But make sure it has enough support for your lower back.
John