I can only comment on the LL2 (original version) vs. the L2, both of which I heard in my system (the LL2 for several weeks), so take it with a little salt. The L2 was more refined, a bit more neutral, with ultimately deeper bass extension (the LL2 was just a little fat in the mid bass, nothing you would really complain about nor really notice but for the comparison with the L2). That said, had I decided on having a Lamm preamp instead of the Jadis I wound up buying, I would have chosen the LL2, because it has more of that tube "magic" as Syntax correctly points out.
I also agree with Syntax that the ML2.1 will really restrict the number of speakers that you can use with it. You really need a very sensitive speaker, and even then there are only a few speakers around that are sensitive enough to let the full glory of that amp shine through. The M1.2s (and for that matter, the ML1.1s I own) will handle far more speaker loads than the ML2.1s. I do not think that either, though, can match the ML2.1's SET magic on the right speaker, good as they are.