[BRX]

My personal feeling is that a PlayTab-like format for manually writing of charts would be great, in particular if combined with the possibility to import iRealPro songs.

I second that. Also it would be great to be able to display chordpro files in a measure-alligned way though I don't know how this can be accomplished best.
I still believe there shouldn't be legal problems for "reversing" irealpro code. It's plain text, not crypted and certainly not intended to protect content.

I probably thought about the BiaB converter for MMA. However, I think I could adapt this converter to produce iRealPro output.

I'd definitely be interested in that, too.