I have mentioned this a couple of times on other threads but last spring I traded in a pair of M60s for M80s inasmuch as I had my heart set on a pair of M80s in the Piano Gloss color and I essentially got a trade-in value that was almost what I paid for the M60s a year and a half earlier so it was hard to pass up. Luckily, it wasn't a moment too soon since, as we all know, unfortunately, the trade-in/trade-up program is a now thing of the past.
In the end, even though I couldn't do a direct A/B comparison, to my ears anyway, I was surprised how similar the two models sounded to one another. If you can afford the M80s and you are interested in the little extra bass extension, you might as well buy them at the outset. As far as the single/ dual tweeter comparison, in an acoustically dead room, any differences in that area, to me, have been inconsequential.
