Did you read this? "to be honest, it makes the style easier to program, not harder. The most difficult thing to do in style creation is designing fills that work for multiple source/destinations. As witness by how many of Korg's styles suffer from just the two fills. Creating a fill that only has to come from ONE place, and only go to ONE place is a piece of cake..."

I honestly don't think that it would be the issue you worry about. For a start off it would be easy to program the fills to use just the two they now provide iF the style hasn't yet been written with the twelve fills (Roland, and I'm sure Yamaha already do this for legacy styles that don't have six fills), but the main thing is how much EASIER it gets to make fills when you don't have to try to make them work for a variety of destinations.

A fill is a one bar event (at least for Roland). Not exactly a huge amount of data, especially if you consider the start of the fill will be very similar to the end of the source destination. Have you tried to make any styles..? I have, but never to my satisfaction. I can get the basic Variations OK, but making just a few fills that have to do lots of different transitions without unacceptable jumps is very difficult. I, for one, would prefer to have to make a lot more fills that I KNEW would only have to make the one transition than struggle with making a fill that worked for several.

But six, or twelve, either of these numbers would be a HUGE improvement in the smoothness of Korg transitions. Let's face it, the jump to six would still be a tripling of the current number (if you discount the B/F), so just to draw even with the competition is going to involve more work for the style designers. Why not make it twelve, and gain the edge?