Just be glad you're on the Axiom board and not Candlepower Forums (
www.candlepowerforums.com/vb). The worst we'll do is tell you to get the 60s... or maybe the 80s...
... but when you ask "should I get A or B" on CPF, the standard answer is always "get them both !!".
Seriously, if you're going to be listening to a fair amount of so-so-quality content (eg. FM radio counts as so-so these days) you might find the M50s actually sound better -- they're a bit more tolerant of bad recordings and media. In most other respects, the M60s have the edge in clarity and ability to play at higher volumes but honestly the difference in sound seems to be pretty small.
Disclaimer -- I have not had a chance to A/B 50s against 60s, just M2, M3, M40 and M60, but by comparing notes with others who had heard 50s against 3s, 50s against 40s etc... we were able to assemble a pretty good picture of how all the models compare.
M60s would not be overkill in your current room, unless the layout forced you to stick 'em right against the back wall (remember the 60s are a bit deeper than the 50s).
You really will be happy with either of them, but the specific symptoms of your ailment seem to include going "what if..." for the rest of your life if you don't get the higher model. That's how we end up with M60s, QS8s and VP150s when in truth a model or two lower might have been fine.
