I guess that would depend on how loud you like to listen. A few reviews have said the M80's need to be pushed a little louder to get the sam e detail as the 60's. My vote is for the 60's, I am running M22's in a room 12 X 27' with the listening area at the 16' mark of the longer spec. the 22's work very well also. Just another option.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70