Well... I can say that I have a pair of M40's, dictated mainly by price concerns. I really, really like them and they never sound fatiguing (a big point for me). I listen some well recorded stuff, but I also listed to a lot of poorly recorded material. I listen to a lot of older punk, rockabilly, etc. Even so, sometimes the M40's still reveal some really poor sound that I never heard with other speakers - like a certain bootleg Clash live record I have, or the Buzzcocks live. I honestly say that I don't think I would be able to listen to it at all if I had a pair of M22 or M60's. I think the "highest" up I will realistically go with Axiom is the M50. I just can't stand the sound of something that is too bright (yet I listen to music that tends to sound that way... go figure).
Since you have a sub... if you prefer a more laid-back sound - I would go with M3's - they won't break your pocketbook, and if you like 'em, you can always sell the M22's - if not, then just return 'em. Shipping on those little guys can't be too much.
Well... I hope I was able to help...
