Demasoni went from M2 to M22 and found a big difference in their "room filling" ability, ie sounded a lot more open when the volume was up. You will probably find the same going from M3 to M22.
I started with M2 for stereo, added a sub, found that the sound was just fantastic except when I started turning up the volume (might have been receiver power limit rather than speaker, not sure). Bought M60s for stereo listening and never looked back.
Now have M60 + stereo setup upstairs, M2 + VP100 + old stereo speakers for surrounds + sub in the basement. Both systems sound fantastic. I picked up a more powerful receiver (HK630) for the HT system which might be helping.
If you think you're going to be doing more movie listening than music, think about getting a sub next rather than upgrading the speakers. On the other hand, if you're going to be mostly listening to music it's real hard to beat M60s...
[EDIT] D'oh !! Forgot you have already ordered the 60s. Never mind
