Hi Dave,
if it was years ago, it probably would have been the BIAB midi tracks, not audio tracks you tried. I think the audio drum tracks were made available with version 2007, then the instrumental real tracks in version 2008. I also doubt they included the audio tracks in demo versions of the program.

I mainly used BIAB midifile tracks as a starting point for my user Korg styles.
Bit of mix n match with onboard style tracks mixed with BIAB tracks to create a style.
Personaly I've never thought BIAB sounded as good as my arranger either.

The Real tracks ( used in the demo's) are audio file tracks , they CAN'T be used in an arranger keyboard for style tracks.

I gather you're sort of familiar with the concept of BIAB ie you type in a chord progression, and BIAB generates a backing track based on the style you've chosen & your chord progression. Earlier versions used midi notes only, newer versions can also use some audio tracks, ie drum tracks, bass, guitar , piano etc
They're actual recordings of live players.
The styles nowadays can be midi note tracks, mix of midi & audio, & I think some may even be complete audio styles.
The interesting part is, you still just choose your style & type in the chord progression, doesn't matter if the style is midi, audio or a mix of both.

Sorry, I didn't mean to give the impression that the audio track styles could be used in an arranger.

best wishes
Rikki