I'm 6'5" and 250 pounds and I STILL got tired of lugging that 9000 around. As George says, the new styles really make the 2000.
I like the 2000, but I'm still mad at Yamaha. Just think, thousands of Japanese losing all that sleep because I'm mad at them.
The above replies pretty well sum it up. What features do you want and need? And how much are you willing to carry? Or you could get a Ketron or Korg.
DonM
P.S. You mentioned the vocal harmonizer. Works great in both. BUT if you need the Karaoke Girl or Speedy Mouse presets, they don't work right on the 2000 and Yamaha will not admit there is a problem. They did come up with a semi-usable workaround. That's like saying "There's no problem, but here's how to get around it."
Go figure.