The Lua scripting is interesting, I wonder if it's possible to basically mix an album with a text file you can check into Git.
I've already made that transition with my music notation projects using Lilypond, I actually have a (very short) full orchestra film score written in Lilypond - full text, nice diffs, revision history, committed to github.
Ardour session files are just text files. Scripts used within the session are saved as part of the session file, so that the session can be used on any Ardour installationg, without having to 'get the scripts'.
I know of a few Ardour users who are using git to collaborate on sessions. Once you figure out how best to deal with the audio data, it seems quite promising.
I've already made that transition with my music notation projects using Lilypond, I actually have a (very short) full orchestra film score written in Lilypond - full text, nice diffs, revision history, committed to github.