Robb,
As a musician myself, I'm currently in the works of putting in a new recording studio, once my theater room gets done. New house ya know, got to do all this stuff all over again.
Anyways, I plan on running M22's. I know Aldo Nova uses M3's in his studio, or at least he was.
In my opinion it really boils down to what you prefer to hear, or how you like your sound. As I'm sure you know, the sound characteristics of the M22's and M3's are quite different. If you're looking for the most accurate in the reproduction, then my personal vote goes to the M22's. That said, the M3's are sweet too and would work extremelly well.
Hope this helps a little.
