I do enjoy using the PSR-S900's harmonizer. I use it about 30% of the time. I agree that it is limited in effectiveness, and sometimes is doesn't track my singing voice correctly. I have been able to edit some of the harmony settings to better suit my voice.

Even though this might be far superior to the PSR-S900's harmonizer, one big disadvantage is that you cannot save settings to the S900's registrations. Each time you want to use a different harmony setting, you have to remember to do it before you start the song - or you might be in trouble.

Maybe I'll wait a couple of years until the PSR-Sxxx comes out.

Beakybird