I use GPO and JABB with Finale 2008 and Kontakt2. Everything works fine, including the GPO drum library.
The JABB drum kits (GM, Brush, & Fusion) notate correctly in Finale, but produce no sound, either during entry or playback.
I won't swear to it, but I think the same problem occurred under Finale 2006 and Kontakt.
The Finale Forum can't come up with an answer, and Native Instruments just doesn't answer. Hopefully someone here can help.