I think that they can work in that room. I used to have a big entertainment unit in my family room and the maggies were 2-2.5' from the side walls and they sound pretty good. Bass was actually deeper. I've player around with my speakers 2-3feet from the back wall. While they sound better pulled out to 3' it was only a minimal improvement. You could probably put some acoustic panels behind them to help.

I use my 1.6's for home theater with a B&W center and no rears because HT sound is secondary to my 2ch listening. I tried rear speakers and thought whats the big deal and why do I need another pair of speakers to clutter my room. The 3.1 set up works for me. Magnepan does make 2 sizes of center channel speakers as well as smaller panels that hang from the wall for HT use. The center channels are large.

If you are concerned about the size, give the MG12's a listen. While they dont sound as good as the 1.6's they do sound very good and are a bargain at $1100. And they sound much better than the MMG's. You probably would want to use a sub with them. The 1.6's dont necessarily need a sub unless you are a bass freak. I don't use a sub, but for 2ch but I have my eye on the Velodyne Optimum 10" sub for when I listen to rock. I have an 8" CH velodyne that I use for HT.

Good luck on what ever you decide. But find a delear and go audition them.