Undo for Audio, maybe... Also WAV handling (not in the same folder, unless you did that yourself - which you should have done anyway) - I don't remember anymore as it's too long ago.
But it was only "destructive" if you used the "offline audio FX" (read: non-realtime stuff) or didn't create a "new version". I never had "destroyed" source files. Maybe because I made copies of it and then worked with them.
