Is there an echo in here?
If you can run a direct radiating speaker for the rear channels I would suggest getting the M2 instead of the M22 unless the plan is to listen to a lot of music. There is very little difference from the M2 to the M22 except a little lower FR and power handling. The M2 is easier/lighter/smaller for wall mounting but if you still plan on the M22 Axiom's wall mount works very well with all their speakers.
The short, short version:
IMO just get M2's for the rears. I don't think the M22's would be worth it for that function. Plus the M2 would be easier to mount.
I jest, but great minds do think a like.
