No problem, except for one thing. Microtonal scales can have more or less than 12 notes per octave. So let's just assume for now I'm using a 13-note per octave scale (though really it could be any number). To hear an octave, I would need to press a combination of notes such as MIDI note numbers 60 & 73. On the piano roll this appears as C and C#! As you go further up or down by octaves, the markings on the piano roll get further and further away from what you're actually hearing in the music. Obviously this is no way to work.
It would be nice as a user to be able to specify the order of black/white notes and specify the number of notes per octave, so the piano roll would make some sense for my music. It's not such a crazy request, actually Reaper already supports this feature: http://www.tallkite.com/forum/index.php?topic=34.0
The Reaper example given above is for a 19-note per octave layout. Reaper even lets you rename the notes, since the usual A-G with sharps and flats notation doesn't work for the majority of microtonal tunings.
Will Ableton consider adding this feature too? It would be great because Ableton Live is so 21st Century with its features, but so 1890's in its assumption of 12-tone equal temperament.
Guys, please chime in with your experiences of microtonal music on Live.
I am also writing a blog post on the topic of microtonal piano rolls and will share in this thread once it has been published.