I went back and did another set of A/B comparisons of the Casio MZ-2000 versus other MP3 demoes.
I ran it against PSR-740, Kurzweil, GEM Equinox, and Darkstar.

After listening to the demoes at length, I have to re-evaluate my original conclusion.

First, many of the contrasting demoes were plain sounds, or amateur compositions. The Casio Demo was very polished and well arranged, almost too good. The first impression was that of a FM radio broadcast, and not of a home synth - which isn't bad, is it? Second, the well mixed signals may have been compressed before making the sound files. A live test must be made before making a decision. Third, the Casio Piano, though not as varied as other, more expensive units, was not bad - and in a live situation, it may be more than adequate for cutting through a mix. Fourth, the emulation of "real instruments" was not perfect, but it's not a Synclavier we're looking at.
Fifth, the drawbar organ wasn't bad at all, but didn't have the "noisy" embellishments that other synths produced - however that might be user selectable. The "rotating speaker" effect was persuasive. Sixth, after listening to the drum sounds, I noticed that the drum rolls didn't sound mechanical or phony - quite a feat. Seventh, the "Lead Guitar" demo had some pleasant surprises, not the least, pick noise, feedback squeals and dramatic pitch shifts ala whammy bar.

I would recommend the MZ-2000 if it was released far below the $1,799.99 list price.
It may not be able to compete with the "big boys" -but- if Casio can get below $899 street price, it would be a great deal - better than the PSR-740. It would be even better if the board had 76 keys.

zZounds is offering the MZ-2000 @ $1,079 (-40%).