John,

If I could sing as well as you, I wouldn't mess with harmonizers at all! I'd just record my own harmonies on a separate track! You'd avoid all the cost, all the artifacts and all the learning curve associated with using a device or program.

There is also the added effect of harmonizing with a person (yourself) who has all the same nuances and timing, which leads to a very pleasing result. And you eliminate the synthetic sound that often makes processed vocals sound fake.

Vocal processors are a necessary evil for people like me who can't sing... but YOU can sing!