Here's the way the PSR2000 style-sync-to-midi works:
"Simultaneous Style & Song Playback Imagine being able to play a MIDI file and a Style at the same time. This keyboard has separate controls for song and style playback. The style will automatically sync to the MIDI file. Maybe you'd like to try one of your favorite songs with a different rhythm. If you are a writer, maybe you'd like to try your song with many different styles to see what it sounds like. If the song has chord data in it (many XG files contain the chord data or you can input it using the keyboard or software programs like XGworks), the style will actually follow the chords in the MIDI file and play a complete instrumental background. It's unique and different and just one of the cool new features of this keyboard."
DonM