I own a pair of the later ML2's which have the brass binding posts. I have not heard the ML2.1 but really like my ML2's. I think the main difference is supposed to be that they had to find a new source for the custom made transformers as they were having delivery issues with the original source. I believe the new source used the same basic specs but the transformers may sound slightly different. I really doubt you can go wrong with either, I have had no maintanence issues with my ML2's since I have had them.
