The M22 and M2 are very similar with respect to how they sound. As you pointed out the M22 is 3db more sensitive ... so, you'd need twice the power for an M2 to get as loud as a M22. The M2 will top out before the M22. Both play well in small and medium sized rooms ... have no complaints with M2's in a 18x18x9 space.
The M22 is a great speaker and Axiom will make one if requested. It's my first choice if you're running a receiver and a sub. If cost or you want something smaller the the M2 is also a great choice.
