There are a couple of things about the Korg's styles that make it almost impossible to use without modifying the styles:
1. Many variations do not transition well when you use fills (mismatched volumes, arrangements get too busy, etc.).
2. Simple short endings are not there. How do you quickly end the song when you need to? Yamaha does it so well...
Once Korg fixes this, it will be hard to beat their arrangers. OS is not an issue... But, if you mostly use MP3s and MIDI files, it is already superior to the current Tyros.