I am one of those that recently moved from M60s to M80s, however, as opposed to what one would perceive as an upgrade, to me it was more for vanity and aesthetic purposes since I always wanted a pair of M80s in the "high gloss" black finish anyway. However, as with any of the real wood finishes, the price can get up there. When I happened to look at the trade-up program and the dollar values involved, I received probably 90% of the original payout on my 2 year old M60s, so really, it was a "no brainer".
As far as making realistic comparisons between the two, although the M80 is the ultimate in the Axiom line, after a couple of months of listening to them, what this showed me, surprisingly, is that the M60 is one great speaker. I use my new M80s primarily in an HT application so whatever differences that might exist, to me, are more subtle. I would concur with "chesseroo's" observations in that other than slightly more highs and a little more bass, realistically, not that much difference especially working in conjunction with subs.
I would suspect that in a two-channel system with no subs, perhaps the differences might be more noticeable. I suppose the bottom line question is moving from M60s to M80s a "significant" audio upgrade? Candidly, I would say not really. Quite frankly, with either model, you can't go wrong.
