I've had plenty of time to evaluate the good/bad of built-in vocal harmonizers, and I have come to the conclusion that NONE of them (including the 9kpro & Ketron) can duplicate the performance that I get from a stand alone unit.
The problem seems to be rooted in a connection to the notes played, whether by fingers or arrangers. On previous Digitech & Korg models, the chord played would simply trigger a midi command that the harmonizer "read" and interpreted as certain notes. On the built-in units, there is always an ON/OFF command that needs to be activated with the button (or FS). This prohibits the use of fast IN & OUT hits of harmony. For anything that's important - I NEED to bring the dedicated unit from now on. Nursing homes get the boxed version.