SRicke:
question: if you move up to master and your subsequent scores take a dive, can you be demoted back down to tour pro? Or are you just stuck?
Yep. No going back.
Your stoke average resets when you move up a tier to whatever your first ranked round score is. So most players have a significant increase in their scoring average when they move up a tier due to the increased difficulty of the new tier.
Moving up a tier often means hitting from tees further from the hole, faster greens, and less forgiving VEM on mis-hits.