I use the TC Helicon Harmony-M, which I set to High and Higher, chordal mode. I use it sparingly, everyone says is sounds pretty darned good.

One thing I learned many years ago from DNJ and UD was that there's an art to using these devices. It takes quite a bit of voice control to obtain the quality you want to use for a live performance. If you do not have that ability, then forget using a vocal harmony processor.

Cheers,

Gary