Tim, since the people who deserve an opinion have weighed in at length, I now feel free to contribute nothing useful to you.

My room is a foot longer than yours. I had M60's for 4 years. They were truly perfect for the room in every way. I now have M100's. They are perfecter.

My rules of thumb are, "Do they fit through the door, and can two of them and me all fit in a room at the same time?"

It's actually an old Rock and Roll guitar amplifier joke, but I think it's a universal truth.

Always call the place you live a house. When you're old, everyone else will call it a home.