I have both - M22's and M60's.
M60's : Atleast 8 inches from back wall gives me good sound although I can live with 4-inches too. Definitely, definitely avoid the side wall. I felt the bass was too strong and kinda booming when the M60's were right up against one of the sidewalls.
I haven't really pushed my M60's that hard (volume wise). They sound as great as the M22's but with more bass. I am sure that in your room, you will be happier with the M60's especially if you like to listen at loudish levels.
My M22's are in the living room (30' L X 11' W X 10' H) and they can easily fill up those 3000+ cubic feet with great sound (receiver volume at 40%)!
M60's are in the bedroom (12' L X 11' W X 10' H).
My main seat when listening to the M60's (the bed) is a little bit on the high side (27"-28"). When I use a chair that is at 18"-19" (as a test near the bedside), I found the details to be even better. I am planning to raise the M60's off the floor a bit for this reason. I know some other people have had similar experience too. I think it maybe because I am seated very close to the speakers (9-feet).
Also both these speakers (I felt M60's are a slight bit more precise) really point out recording mistakes (level problems, abrupt transitions, background noise, etc).
On my previous speakers (Bose / Sony), I had never heard these details (irregularities) in the recordings (I have been listening to some of these songs for the last 12 years).
You may want to demo these before making the actual purchase. Look at the foll. link
to see if anybody in your neighbourhood is willing to let you listen to any or both of these...
Good luck in your decision.
Cheers / Mahesh