If wall mount is your best option, I would agree that the M22 + sub is the best (Johnk would certainly agree).
The main reason to keep speakers away from the wall is to avoid unwanted bass re-enforcement (boundary effects). When using a sub, you may be able to negate this by moving the crossover a little higher, thus removing some of that bass from the M22s and re-assigning it to a properly placed sub.
I was thinking that you were going to put the M22s on stands, in which case they really take up the same footprint as a floor standing speaker.
