Gary, I think, when push comes to shove, that your vast collection of Yamaha styles is what is going to keep you in Yamaha's camp, no matter how much 'better' the PA600 might appear.

Style conversion is still a pretty much hit or miss affair, and incredibly time consuming to do right. There's much to admire in a PA600 (it's got a Chord Sequencer, already!), but it still suffers from the age old Korg Achilles Heel... nowhere near as large a pool of factory and high quality user styles available.