I have a pair of M3's and I've listened to M22's before (although not at high sound levels).
I would say it comes down to personal taste. The M3's are laid back and the M22's are forward. I am very impressed with the M3's but if I could swap them for M22's I would most likely do that because of my personal taste.
A lil more about my experience with the M3's... Being that they are more laid back I've found even at dbs in the mid 90's that the sound is still pretty clear and not overly fatiging. At low levels I think they sound extremely *comfortable*. In fact I'd say these speakers maintain a pretty consitant sound no matter how loud you like your music.
