Ian,
I have had both T2 and PA2 at the same time.
The OS thing is somewhat personal.
But, what I can tell you is the Yamaha Tx OS gets the job done and is nice in some ways...but if one wants the maximum flexibility and programming/editing the Korg is FAr superior...
Just depends on what you need.

This time I will go with which ever keyboard SOUNDS best to me for what I play...and the OS will just come along for the ride.
Also, I will pat close attention to the styles...I do not want only simple styles????
_________________________
Lee S.