Scott,
Glad you are enjoying your PSR2000. I bought mine in the beginning of August and have been enjoying it every day.
So far, for how I play, the styles have been acceptable to me. I have only my PS55 to compare it to and that only had drum not styles to back the tunes up. I had tried the 550 and 740 before I bought this (untried and unheard) based on the suggestions of this group! I try to play at least an hour every day on it and learn at least one new thing each time if I can.
I also understand about the color-blind situation. It is difficult to design an interface to accomodate everyone. I built a web-based system for a client and the interface had color coded indicators to let them know the progress. It turned out my main user was color-blind! He joked about it at first but I also included the words right next to the colored buttons that would indicate the same thing! Pretty much like the main screen indicator counters.
I like the OTS link on the styles and have used that very often to change beats/instruments in a song to make it sound more alive. Even the fill-in when switching makes it sound like I'm doing more than I am.
On the negative I would pick the intros/endings since most of them don't really match my songs but once in a while I get lucky with them. I mark all of my music when to switch styles/instruments/breaks, etc. and than helps as well.

Squeak,
I liked your suggestion on the tutorial on diskette. (or more than one) and use the memory for improving/adding other functionality. I also agree with Joe that it is a nice feature to get a "feel" for all of the instruments and how to use them.

Really enjoying my 2000,
- Brian