I was just in the store tonight playing with the 2500. It's only 16 bit, but there is something about it that makes it sound cool. Not sure if it's the timing, converters, etc. But it definitely "frames" the sound into hip-hop.
Hilariously simple device. But cool.
Haven't tried the 4000 or the 1000 yet. Only the 2000, 2500 and 3000.