How does that square with the answer to #44 in the FAQ:

"Can I replace any MIDI track with a RealTracks instrument? Yes, you can replace any MIDI track in any Band-in-a-Box song or style with the RealTracks instrument of your choice. You can have any combination of MIDI and RealTracks in your song."

http://www.pgmusic.com/salesfaq1.htm#34