More fills... Probably one of the things that screams 'arranger!' more than anything else. You'll rarely hear a drummer play the exact same fill twice, unless part of the original song. But four fills for a four Variation arranger rarely allows you to NOT repeat at least one of them a bunch of times.

You need 16 fills for every possible combination of source and destination Variations (including Fill-to-Same), which only illustrates how few four are. Yes, they are MUCH better than the mere two Korg had before the PA3x, but Yamaha and Roland already are running six, and hopefully up that number soon.