I'm looking for a beefed-up replacement for my dear psr530. I'd like a more powerful sequencer, a disk drive for loading custom styles, etc and storage, a good-sounding amp/speaker section. Voice harmonization, if it really works, would be great. Can anyone let me have their opinion in regard to the psr2000 vs. the psr9000? What are the main differences and is the extra $1,000+ for the 9000 money well spent? I plan on performing rather informally and doing some composing. Thanks.