De-facto standard: Mudcat posters may well check thir tunes with mandolintab, but if they want their work to survive for another year or two, they are best advised to dispense with all those extra features of abcm2ps that are not contained in ABC 2.1, or are declared "volatile".

MuseScore: somewhere I read that the programmers planned to implement direct import and export of ABC, as soon as there is a stable standard. Until then, Mick, your own programming efforts may be welcome. The author of those Python tools updates them frequently, he can be googled as an "abcusers" member.

For my own occasional ABC needs, I use a notation program that predates MusicXML but with which I am very quick, and export the tunes to ABC via MidiZyx2abc.jar, then if desired to MusicXML via abc2xml.py. I agree with Artful that this is a makeshift; newbies will be better off with programs for which MusicXML support is available, e.g. MuseScore.

Mick, you seem to be a dedicated programmer; your efforts for our goal are greatly appreciated. The same applies to anyone else who can work for the standard we need.