I am a side sleeper that sleeps very hot and has low back pain every morning when sleeping on a very old traditional mattress with a memory foam topper.

I did alot of research along with testing out all the Casper models at a local store.  I originally decided on the Casper Wave mattress but it was still a little too firm for me (especially on my shoulder).  After a very easy return, I switched to the Casper Wave Hybrid and it has been great so far.   It has the right combination of softness and support and I sleep much cooler than I ever did on memory foam.