I've never used the M-one XL, so my comments are based on the original M-One. I should also say that my comparison was done over a year ago, probably more like two years, so it's possible that newer firmware releases have changed things.
So, when I compared the two, it was in the pro audio department of a local music store, on a slow day with almost no background noise. The store had a switching system setup to be able to switch processors in and out instantly, making a/b comparisons easy to do. I went in as a long time Lexi fan who had been told by a couple of people that in that price range I should really listen to the M-One.
I can't remember what the mic was, but I listened to both verbs with acoustic guitar, finger snaps, stick hits, and vocals. The difference was shocking to me, so much that I wondered if something was wrong with the Lexicon. The Lexi had that thickness that I expected, but the tails were terrible. They sounded very artificial, with a sort of looped repetitiveness that betrayed their digital nature. The M-One on the other hand sounded like the natural decay of a room, and was more realistic by a huge margin.
I think that some people would prefer the Lexi for it's somewhat fatter sound, but to me the realism of the TC trumped that. It might have a lot to do with the kind of music you do. I work with a lot of acoustic instruments, including guitar, mandolin, piano, violin, viola, cello, etc. For me, realistic was the deciding factor. For more electronic stuff, the fatness of the lexi could be better.
Hope that helps a little, RD
