hello,
we did it about one month ago. It was painfull. new domain, new server name, new ip
we reinstalled 8.1 fresh and restored the database, we had to open a case with tech support and Ron LeBaron and he was able to solve all the issues we had after the move.
on the old NS, we redirected old agent to the new server
finally, to follow the % of computers migrated to the new NS, we create a policy with a package that create an empty file. this way, migrated computers get the policy, the file is created and compliance show how many computers are moved.
(I'm leaving for 4 days so I won't reply until next tuesday if you have more specifics questions)
good luck!