I might just buy an outboard harmonizer again, depending on the results I get with the TC built in one. I used to have a vocalist by Digitech, and loved it. Just set the key, and forget it. Real good sounding harmonies. The one at the link below, I have not heard of. Maybe someone has one? It has pitch correction, which I could certainly use from time to time. Needs no midi, guitar or keyboard signal. But has midi in/out, mic, and guitar in, etc. if you want.

http://www.digitech.com/products/Vocalist/Vocalist_VL3D.php