Donny - I just went through the entire menu of choices for the footswitches, and there is no setting for harmony on/off listed. The choice for mic harmony volume is meant for a continuous controller, like an expression pedal. As far as I can see, there is actually no way to turn the harmony on and off with a pedal. That'd be a deal breaker for me, if I was using it only ion the studio. Disappointing. Maybe an oversight?
I'm setting this reply in it's own post, as I think it's a huge issue for potential users.