Wow, that IS a tricky choice for you. If it helps, IMO the only way you can have "too much speaker for the room" is :
(a) you pay more than you have to and don't get much better sound
(b) you piss off the rest of the family by having "those big ugly boxes" in the room
(c) you have to put the speakers closer to the wall or corner than you would if you had a larger room, so close that the bass reinforcement off the walls/corners makes the speakers sound boomy or otherwise bass-heavy
(d) you turn the volume up too high and hurt yourself
Seriously, either system would work just fine in your room. In my case I bought M2s and a sub and was totally blown away with how much better DVDs sounded... so much that I flipped over from being a "90% music" listener to more like 50/50.
M22s will sound about 99% as good, but you want M60s. Figure it out, dude
