tom: Thanks for your comments & kind words. My Velo is over 20 years old & has to be on its last legs. I have occasional 'Gain Control' issues that is common to the 'F Series' when they reach their senior years - it's just a matter of time before it becomes a door stop. I have a pair of M22s downstairs in my HT & really like them in that setting; however, with the high end finish, the M22s are $170 more than the M2s which is stretching it a bit.
Joe: I already have two M3s hidden away in this room in my separate ambiance system as described here in my other thread 'Auction Win - M3v3s'. They are more than able to fill the 3900 cu ft with moderate levels of quality sound. My reasoning for considering the M2s is that the M2s' SPLs are rated at only 3 Db lower than the M22s, 2 Db less than the M3s & surprisingly 1 Db more than my present AX2s. Therefore, I didn't think that the M2s would suffer here at the moderate levels that I enjoy now.
dak: I wanted to get away from the large form factor of the bigger subs & satellites in this setting. If I was to go with 2 larger subs such as the EP-350s/500s, I'd probably use them as stands for the M22s as I have done downstairs in my HT. Cost for the finishes on all of the bigger speakers also becomes a factor.
The EP-400 to me is a really nice compromise for size with accurate, fine performance. It is even smaller than my 14" cube F1000. I don't think that my wife would entertain the thought of a bigger wooden box sitting in the alcove. With the M3s newly installed in this room's corners, I'm really pushing it!
Cost is certainly a factor & I have to get this done prior to my wife retiring next year, ha!! When high end finishes are factored in, the M2s + EP-400 combo is by far the most cost effective solution due to the smaller area of the veneers requiring finishing.
Thanks all for your thoughts & insight. I eagerly await any more words of wisdom from the fine folks here...