I started with a Digitech Vocalist 4 floor pedal model and have tried several different things mostly through rentals. Haven't found anything better. I wanted a PSR S950 but VH2 is so bad I bought the 750 instead and run my Vocalist through it.
Sometimes I think I hear decent harmony with VH2 but the whole processed sound is very unnatural. Even the lead voice becomes garbled when harmony is engaged.