I just moved from stock 2.2 to Fission 2.1 final last night - everything went smoothly and it seems to be working well! One problem I've found though is that my phone is now unable to play any music. The Android Music player gives an error that every file I play is not supported by the music player, Pandora just hangs when trying to play, XiiaLive gives a media player error, and even Winamp gives an error that it can't play anything. I've tried clearing data for the Music application, reinstalling both Android_Music and DX_Music from the Add_On directory, battery pulls, etc. but nothing seems to work. I've heard of a similar problem happening on Moto stock firmware but I never had this problem until I flashed to Fission 2.1.
Any ideas? Thanks for all your hard work on this - it looks great!