Hello:

You can change the STS without having to use a "User Style" bank location, in other words, Korg allow you to customize your keyboard, like changing the STS on any style in the SAME style location and it does not matter if it is a Factory style or user bank style.
You can also change the whole style or style parts, providing you can use just about any sequencer, as simple as changing a midi file.
I also have the T2, I can tell you that the Korg instrument is much more flexible in certain areas, for example, you can load user styles into the Factory style banks...you can not do that in the Yamaha, etc.
The Yamaha T2/T3, and the PA 800/2X is a GREAT combination, I always use those 2 arrangers.
Is just matter if you like the keyboard, make the best of it.