Fran,
  I totally agree with you about the MZ (still) being able to compete with the others (even though it's over 4 years old).
  One thing is the MZ has REALLY good voice editing.  PSR's (not even the PSR-3000 can touch the MZ's voice editing capabilities).
  The MZ also has real-time sliders (PSR-3000, and down does not), and you'll get aftertouch with the MZ-2000 as well.  It also has much better quality pitchbend and mod wheels.
  It's amazing that Casio put this beast out, and it's a shame the public didn't take to it (Casio's 80's reputation probably had a role in that).
  I really hope Casio does it again.  The MZ when released competed with the PSR-740, and man did it BLOW the 740 away in so many areas. 
  I think a MZ-3000 to compete with the PSR-3000 would be great.
  Oh I also agree with AJ that the MZ was a killer Rompler.  There was that warmness almost analog feel to the sound.
Squeak
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GEAR:  Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller).  SOFTWARE:  Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.