Hi Wdkomo,
A few comments addressing a number of your questions:
Without using a subwoofer, the limitation of ALL small-enclosure bookshelf speakers is deep bass extension as well as overall bass output. In the room you describe, with either the M22ti or M3ti, a subwoofer like Axiom's EP175 would be essential. If you have area rugs, get the M22ti for their wonderfully detailed soundstage and clarity. If you have bare floors, the M3ti has a tad less midrange output. If you have typical furnishings (area rugs, upholstered furniture, etc.), the M22ti's are not "bright".
The floorstanding equivalents of those two bookshelf models are the M60ti and the M50ti, respectively.
As to Boston Acoustics, while I have not heard the models you mentioned, a general comment would be that Boston's strengths always lay in their least expensive small bookshelf models like the old A40s, A60s and A70s. Overall, Boston is not in the same league as Axiom in terms of neutrality and natural uncolored sound reproduction.
Comparable speakers to the M22ti in terms of tonal balance and neutrality are the Paradigm Reference Studio 20s (I own a pair). The Paradigms have a bit of a bass "hump" centered around 80 to 120 Hz that causes male vocals to sound a bit bloated or "fat". On first hearing, the Studio 20s give the impression of having more bass output than the M22s or M3s; in reality, they don't go any lower than the Axioms. The bass from the M22s and M3s is smoother and doesn't have the hump.
Regards,
