Disabled channels would function identical to muted ones (Zxx and PC events are still read), however they do not toggle ON when you press "Unmute all".

This would be a big help because I usually have to have a metronome channel. Everytime I solo a channel and then press "unmute all", the metronome channel turns back on. I only want to hear it in very specific (and rare) circumstances. Besides metronomes, this feature would be helpful when working with vocal scratch tracks so I can keep the vocal channels muted while mixing the instrumental underneath.