I'm 99% sure I'm going to get some M22s for my study. (Got my son some M3s and I loved those.) It's a smaller room, ~14x13; so if that's not a good mix I'd be interested in hearing so.
Don't know if you are afraid of overpowering a small room...but don't be if this is your fear. I have M22s in a room smaller than yours (11 X 13 X 7.5) and I never feel that I have "too much" speaker in the room.
Can't tell you about the horizontal orientation, as that never crossed my mind...but, like stated above, I've heard that the correct characteristics and dispersion of the M22 depends heavily upon vertical orientation.
I also am not sure why you would be wanting to crossover at such a high frequency. I believe that 80Hz is recommended by Axiom. My Denon AVR (1910) wants to set the crossover at 40Hz during automated setup...so I think that you should get a good response out of the M22s down to at least 80Hz.
One thing that I have learned is that sometimes it is better to have no subwoofer at all than a really cheap one. Once I moved away from my 8-inch $90 Sony sub (ah...those were the days
) to the Axiom EP350, I realized just how horrible, bloated, and inaccurate cheap bass is. I would much rather have no "low end" at all than have to listen to that crappy booming again.
