We did try Windows RA and it does work fine for in-network support. It did not work for external employee's. We have since tried Dameware and that works OK for both. We are currently testing Teamviewer to see if we like that interface better than Dameware. Both TV and Dameware work, now we are just figuring out which one we like better.
For in network support we will probably use Lansweepers Remote Control. We are used to it and it handles UAC prompts fine.
I'll update this after we make our final decision, maybe it will help someone trying to do this in the future.