Hey Big...I'll be watching this post carefully. I too have a room your size (except for the ceiling....mine is 8ft). From what I understand the Soundlabs don't bother too much for the ceiling height. I believe (and Duke and Brian I hope will chime in) you can do well with the M-3's as well as the M-1's! I have a bit more complicated problem as my 16 foot wide listening spot is taken up by my front door to my home. Therefore the speakers would be placed in a spot that is only 9 1/2 feet wide. I listen also 8-10 feet away and my depth is 27 ft.
RWD
RWD