I really think that you would do great with the M60s in a room that size, and think that you would find they are really no compromise in your needs.
Both are great speakers... the M80s just play louder in a very large room (larger than yours). As John said, the Yamaha would probably be OK with the M80s under most circumstances, but why take that chance if the M60s are 98% as good as the M80s in all but gigantic rooms?

::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::