I have never owned a Casio, but tried helping a friend who bought one. All he cared about were the organ sounds...and they were good. But, I had trouble with navigation.

The Roland EM2000 styles felt too busy to me and many had l-o-n-g endings and only two variations.

The PSR2000 required a little extra effort to understand the operating system, but I love the styles, the speed, the lightweight, most all the instruments and editing capabilities. Because of it's "economical" construction it requires a little more care in handling...but overall, its the suits me best for the one nighters I play.
Eddie