Here is a spot where I would like to try some M80's. The room is about 13 x 15 but is is uneven because the wall is bumped out for a bookshelf behind the couch. I think the ceilings are 8 feet. The chair is too far forward in the picture. I pull it back when I watch a movie or listen to music.
I think the 60's would be fine and maybe even the 50's but we all know what happens right after you buy 60's.
Other thoughts were M2's or M'3s with a sub. If I get a smaller speaker I can afford a high gloss finish.
And I know I need curtains. I have been living here for 6 years now and I plan on getting to it someday.