earlier I wrote:

'On the Roland and Korg, you have to record the whole arrangement in real time, which is ridicolous'

just toclarify: you can write the chords in step time on the Roland and Korg too, but you can only do so for EACH TRACK SEPARATELY, while on the Yamaha, you can do so for the FULL BACKING at once. You write the chords and the fills and the whole rhythm section is programmed. End of story.

On the Korg and Roland,you can do the full backing as well, of course, but you HAVE TO WRITE THE PARTS FOR EACH INSTRUMENT SEPARATELY. So it's like you compare writing the chords ONCE to writing the chords 8 times (depending how many instruments play in the accompaniment for the chosen style)

That's where the real difference is.