I have compared the M60v2 and M80v2 and the midrange is where there is more of a noticeable difference to my ears and there is also a tad better lower end to the M80s. I also noticed the M80s play a bit cleaner/crisper at lower volumes but only really noticeable doing an A/B test.
I would recommend you order up a set of M80s, compare them to the M60s and make the decision on your own. I think it costs about $90 to send the M80s back should you decide to not keep them. I have wasted that much cash in fuel driving around listening to speakers on an afternoon.
