I’ve just upgraded my Hyper-V lab box to RTM. It took maybe about 10 minutes (most of that was POST during reboots) to install the update and another 5 to install the updated enhancements in 8 VM’s. It’s a very easy process as John Howard describes on his blog.
EDIT:
Snapshots are supported between RC1 and RTM. They are not support between either beta or RC0 and RTM.