I think Spiffnme hit the nail on the head with point #2. If you don't have a good quality sub in an M22 configuration, bass reproduction will suffer. Since the M60s provide sufficiently accurate bass (certainly lower than the m22), a lot of people prefer to listen minus the sub. Heck there's M60 owners, like regular Chesseroo, that have a high quality sub and barely use it for music reproduction (50hz crossover) preferring the M60s to produce all but the lowest bass.
This is most likely the reason that the M22s don't get the same consideration that the M60s do, it's the subs fault, not the M22s.
