So all the components finally came and I had a chance to compare the M80s to the LFR660s, and ... I liked the M80s better. I'm as surprised as you are.
It wasn't hands down; I'd say about 40% of the music I used for the comparison sounded better on the LFRs. (I used old/new recordings, a mix of rock/blues/jazz/classical, and a mix of acoustic/vocal.)
I'd say the imaging on the LFRs was better across the board, but I found that that aspect didn't matter to me that much. Another significant difference to me was that on the M80 the music generally appeared to come from the speaker, whereas on the LFRs it came from a right/left column (horizontal separation was pretty close between them), and I definitely liked the LFR vertical presentation better. On the other hand the M80s sounded more punchy/dynamic. (I did adjust for volume, but not using a meter.) But what really swung it for me is that the songs that that I really enjoyed, the ones that put a smile on my face, were on the M80.
Maybe the problem was that I really should have been comparing M80s to the LFR880 or M60s and LFR660; but there you have it.
Another interesting tidbit was that my wife liked the M80s better too (in more-or-less blind test; I didn't tell her anything and she kept her eyes closed). After her selection I filled her in and she posited that our older ears are losing the highs and the M80 compensated for that more. It makes some sense.
And in passing I'll add that the M8- sounded much better with the ADA1000 than using my 10 year old (8 ohm) Onkyo. Shocker, right?. | 
