If you're going without a sub, you might be more happy with the M80's. I own M60's and have heard M80's on several occasions.
I think the M80's play louder and deeper. Jakewash has made excellent comparisons between the two, and I believe his impression is that even at lower volumes the M80's are "better". I haven't had long enough exposure to them in a known environment to validate that for myself, but I do trust Jason.
All that being said, I have M60ti's and I think they are really pretty fantastic.
