tony,
Now i understand what you are getting at by saying you only have 10".
However both of the QSx speakers are under the 10" height with the QS4 only being 6.5" tall. This gives plenty of space to put 1" rubber feet underneath to allow for the bottom woofer to fire more openly.
I have one of my QS8s sitting on a shelf right now and it works fine. I can post a pic if necessary.

As for the M60 vs M80, according to Alan & Ian, the M80 simply has more bass extension and plays louder. That's about it.

"Those who preach the myths of audio are ignorant of truth."