Ken is correct about the matching imaging, clarity and soundstage for both speakers. He's also correct in that the bass provided from the M60s is no substitute for a good sub. But, the bass provided is superior to that provided by the M22s (I've owned both in a room 11.5x18x8). If you intend to get a sub at a later date, I think getting the M60s now, is a good idea. It will provide acceptable bass with music, and they'll be just passable with movies. However, when you add that sub, and I recommend you do as soon as it's feasible, you WILL discover what you've been missing.
I've got no opinion on the "dial in" theory. I know that the M80s are a little more difficult to position accurately than the M60s, but I don't know if that also applies to bookshelf speakers compared to floor-standers.
Both the M22s and the M60s can be placed as close as 3 inches to the wall behind them, though It's my personal opinion a little more space would be better. But, 3 inches is all the space needed for the rear ports to "breathe" properly. So, you don't need to worry about that.
It's your call.
