Hi again,
Looks like you have received some good advice, expecially from Ian Stewart. Ian is VERY good and would be a good resource for you. he'd be the guy I would call anyway. We are completely unrelated, so I'm not just endorsing a friend.
Regarding demos. Many resellers that I've seen do not really do phenominal demos. The best ones I've seen are done by Microsoft themselves. It's my understanding that the reseller can set these up; I may be wrong.
The 'financials' aspect of GP is probably it's strongest feature. I like the Collections Management module. Nearly all of my clients have it and love it. You should be able to get a stellar demo of those features.
From an end-user point of view, Integration Manager is the easiest solution to set up and modify. When I say easiest, I mean easy for the end-user to modify and create new integrations themselves.
Looks like you're on your way! I think you'll love Dynamics GP once you start using it and getting away from QuickBooks.
Kind regards,
Leslie