Hi BigRed,
Not to further complicate your choices, but there is a tiny issue that hasn't been fully addressed here. There is a slight tonal difference in the midrange between the M3 and the M2 (and M22s). It's nicely described by another Axiom regular who owns M50s and just got new M80s. Kcarlile called the M80s a bit "crisper" than his M50s, which is exactly how I'd describe the subtle--but audible--difference between the M2 and the M3. The M2 (and M22) have just a touch more detail or crispness in the upper midrange over the M3. Put another way, the M3's mids are a bit "laid back" compared to the M2's and M22s (and M80s). So are the M50's mids. To echo JohnK, the M2 is really an amazing speaker for a small room, and coupled with a sub, they hold their own in medium-sized rooms.
I'd rephrase the line about the center channel being the "most important" for home theater. You certainly want clarity for dialog, and neutrality, but the main left and right speakers still reproduce the bulk of musical content and effects that are not dead center, and thus assume a more important weight than the center. You can tolerate a lousy colored-sounding center so long as the main left and right are neutral and musical. I'd find it impossible to live with crappy main channels and a fine center.
Regards,
