FYI:
Here's a link to Yamaha's Website listing the features of the PSR2000:
http://www.yamaha.com/cgi-win/webcgi.exe/DsplyModel/?gPPK00005PSR2000

It clearly describes the 2000's Flash ROM OS feature (see bottom of page). Right underneath it (in red letters) it says: Features subject to change without notice. Funny, I never noticed that before. I guess that means, with this clause, they are legally free to eliminate (without notice) just about ANY feature they want to: the vocal harmonizer, any sounds (voices), styles, OTS, etc. . . hmmm.