Axiom Home Page Forums General Discussion Home Theater hybrid tower?

I should have given a little more detail in my initial post. I intend on picking up another M2 from the FO and using that eventually in a second zone. The second zone won't get set up for some time so in the interim I'm curious about using the M2 stacked on the M22. The idea of utilizing the M2 as a rear interests me. I've got the issue of my room layout to contend with. My sweet spot is on a sofa which sits right against the back wall of the room-9 feet from the tv, m22's, and VP150. The surrounds (qs4's) are by necessity also mounted on the the back wall. I could easily mount the rear between the surrounds. The surrounds are about 12 feet apart and approximately 7 feet up on the wall. Does anyone have any idea what a rear speaker mounted directly above the sweet spot (especially an M2) will do in a system like mine? What role does the back speaker in a 6.1 mode play? I'll probably give it a shot just out of curiosity. I appreciate all your input.