Grand conversion results, aye, so thanks for yer hard work!
There seems to be some quirks and bugs, though, related to saving and exporting files. I heard of various things so far. One thing I have seen myself is related to editing old .abc files. That was very useful in the previous version, where you could go in and update track information directly through Maestro, or play with volumes, without using a text editor.
However, if you edit an old .abc file in Maestro 2.0 (for instance, files created by Fireferns or LOTRO Midi Player), the exported file may end up almost empty of information. For the few files I have tested on, only the song title header remained in the exported file. Which is a bit sad if you just overwrote the old version.
So keep a backup of your files before you try editing old files. And fingers crossed that this is fixed in an update, it really is a grand converter.