First, thank you for creating and maintaining such a fantastic resource for percussionists.
I upgraded to Finale 2010 today after using Finale 2006 for a couple years. I currently use VDL 2, but plan to upgrade to 2.5 in the next few weeks.
But until I upgrade and use 2.5 and its templates, I was wondering if its possible to use the Finale 2006 Template in Finale 2010, and load VDL 2 as a VST/AU. This is simply so I may continue to write pieces I have in progress right now, but use the new features in Finale 2010.
You could give it a whirl as you're proposing and see what happens. However, VDL:2 (built into Kontakt Player 1) isn't officially supported on Leopard, so your mileage may vary. Once you get VDL 2.5 and its updated KP2, you should gain a lot better flexibility. If nothing else, the ability to load more than 8 patches per plugin instance is big convenience, and resource saver.
It should still work just fine as far as the VST loading goes. You might run into trouble with the new mapping stuff that has changed from 2009 to 2010. The following FAQ should apply to Finale 2010 in much the same way as Finale 2007: