Each arranger I've owned had different features that were the coolest for me.
The MZ2000: Midi to style creator and detailed synth editing
The PSR740: Instant style groove function
PSR2000: Better mixing section than the 740, very decent decent vocal harmonizer.
PA80: Style morphing, great sounds, excellent flexibility in editing, and the coolest of all, the ability to replace internal styles at will. Honorable mention: A joystick instead of pitch / mod wheels.
Fran, the two sequencers of the PA80 are available so that you can fade from one sequence to another. They can both play simultaneously or you can start one just before the other ends and do a fade..etc. As Dave says, there is no down time between sequences at all.
AJ
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AJ