The RealStyles made for the
Xtra Styles PAK use the complete RealTracks library that is included in the larger packages (UltraPAK, UltraPAK+, Audiophile Edition).
So, Xtra Styles PAKs will work when you have all
3,500+ RealTracks installed. Since the Pro version has roughly
590 RealTracks (and the MegaPAK approx
800), it would be
incredibly difficult to find substitutions with the limited RealTracks & RealDrums included in that package.
That's one of the reasons we began developing the XPro PAKs - this way no one misses out on using new RealStyles with their Band-in-a-Box package.
-Callie