Ardour and Reaper use plaintext project formats that work well with Git, at least for basic versioning.
> Regarding plugins, I know that I'm not the only lead developer of a DAW who, if they possibly could, would refuse to support plugins entirely. The problem is that most users want more functionality than a DAW itself could feasibly provide (they also sometimes like to use the same functionality (plugin) in different DAWs or different workflows).
I think the answer to this would be something like Reaper's "JS" plugins, which are written in a small compiled language and distributed as source code. Compared to "JS", it would need to: 1) be open source; 2) be a better language; and 3) support pretty skeuomorphic graphics ('cause people seem to really want that in their plugins). Ardour seems to be working on something like this using Lua (don't know about the graphics, or if the plugins could be supported in other DAWs).