A second microphone track.
A second microphone track would provide considerable benefit. Musicians may want to have two separately recorded instruments or possibly a VoiceOver track, as well as, an acoustic instrument track. Right now with only one option for a microphone recording this can't be done. It would also allow two moderators to have a discussion or a debate. I believe the addition of a second microphone track would be of immense benefit. Although I'm not a programmer, I would think that just reproducing the microphone track, that exists already, would hopefully not be too difficult.