I have the QS8s but I think I can help out a bit here.
I originally had M3s as my surrounds and they were next to the ends of the couch facing in about ear height and slighty behind on make shift stands. The sound was good, but fairly localized. Then I read a suggestion to move them at least a foot above the ears - big difference.
Eventually after reading so much about the QS8s I caved - WOW! Talk about dispersion! I can't say enough about how impressed I am by the design and the ability to create local OR dispersed sound. I'd imagine the QS4s should be similar.
I'd lean toward wall mouting them and save the money (sorry Axiom) or put the money towards QS8s (you're welcome Axiom). I'm not sure that the full benefit of these is realized at 36" off the ground.
