Actually, Korg is the ONLY arranger that still has fill buttons, and that is on the 4x. The fills are integrated into the style variation buttons, and there are a couple of modes you can use to control how they work.
Yamaha, Roland, Ketron, all work the same way.
Thats definately where korg shines on the pa4x...
Hope they will add the performance memmory which makes Genos shine back in the pa5x..
Won’t be long now before korg announces a new pa5x..