I have no experience with tempurpedic beds, but I have two degenerative discs on my lower back and one on the middle of my back that I nurse every day. If I shovel snow or rake leaves I am sore for days. There is no way I could ever sleep on a soft or foam mattress. I absolutely have to have a rock hard bed - a regular hardest available mattress. The kind that hurts my wife’s shoulder while she sleeps, but which allows my back to stretch and fill my discs with fluid. Honestly, I would sleep on the floor if it worked better, but a hard mattress works just fine.
I view foam mattresses like water beds - great if you want back problems.