I have the digitech live 4 what a great sounding unit.
I've preordered the tc harmony m and they are still talking about a june 30 ship date I'll let ya know if I hear any different.

I like the pedal setup on the live 4 if it had midi I'd stop looking. It has great vocal channel preset effects that really makes the vocals come alive. I might keep it just for that reason. Look at the live 4 video on the digitech website.
And the pitch correct is better than I've ever heard you can set it to chromatic and you don't have to put in the key or trigger it with any chords.
The voicelive pro is the rack version with both midi and guitar. Costs $100 more than the live 4 should have gotten that one. But I do like the pedal.