Hi dharris,
Welcome. Since I just dealt with an Axiom customer yesterday on this subject, here are a few thoughts on your situation. I do think the general dimensions of the room suggest our larger bookshelf models, the M22s. They will have greater dynamic capabilities with your subwoofer in the larger space.
Note also there is a slight but quite audible tonal difference in the M3s and the M2 or M22s. The M3s are a few dB down in the midrange, so they have a slightly recessed or "laid-back" midrange compared to the M22s or M2s, which have a bit more detail and clarity through the mids. Lots of customers like the slightly softer mids of the M3s, but many prefer the detail and transparency of the M22s. Tonally the latter are very close in the midrange and highs to the floorstanding M60s and M80s when the M22s have subwoofer support.
Regards,
