Since the room modes will be closer to each other in a small room, lets say every 50 or 60 hz, I think that you will have more acoustic problems. Also a 12 x 12 doesnt sound good, because its proportions are the same.
In a small room you will have more bass problems, and you will need to add some acoustic treatment to clean the soundstage and the image. Speaker and listening position experimenting will also help a lot.
Alan Brain