The VP150 isn't ported so it won't play quite as low as the M22's and I suspect a pair of M22s will play virtually as loud as a piar of VP150s give or take a db or 2. IMO the M22 plays a touch smoother than the 150.
If I were you I would try the M22's and if you feel they are lacking then I would move up to floorstanders, M60/M80, the Vp150 is a good speaker but was not designed to be used vertically and as such the sound quality can't help but be compromised. For example, I tried the VP180 vertically against my M80v2 and there was a noticeable difference. The Vp180 couldn't touch the soundstage the M80 could throw out. The 180 was still clear and sounded quite good but not as good as the M80.
