I've owned and gigged with the Tyros 2 and Korg PA800.

I agree on some of the Korg fills are out of no where with volume and the amount of instruments compared to the variation you were on.

the T2 fills were very smooth almost to the point of not even noticing they were there.

The T2 had more styles that were song specific, meaning the style was based on a certain song rather than a style. could be a good point or bad.

The T2 vocalizer was a slap in the face to professional musicians, a $3000 plus keyboard with a $5 vocalizer.

I like the T2 OS but the more I use the PA800 the easier it seems to be.

T2 had some incredible signature sounds that are amazing.

Midi file playback hands down better on the PA series, better deeper fuller bass and drum sounds, I always had to eq each style on the T2, adding bass and treble to the drums and raising the volume.

The PA800 has a more open live type sound, as the T2 was more compressed finished sound.

They are both top line arrangers, of course with the "blue " of the 800 and the Starship lights of the T2, it's hard to see who is the more professional looking.

As for the PA800/2xpro compared to the PA1x series.

I had both series in my possesion for a while and once you really start playing and listening, it seemed the newer series had a nicer tone and overall balance, not by much but it did.
plus the newer USB stuff, Polyphony, lighter weight. May not be much but it is a step ahead.

sorry for the long post