The changing hostname topic does not work reliable for me (for example despite the remap+rebake the twitter-emoticons of the Welcome post point to wrong server) - havent researched why that is (will let you know). At least its not painless.
The redirect for my usescases does not work since it would redirect to the old server
nginx config does not need a change its not aware of the hostname. But the problem is more with the app, for example the CSP headers contain the full URL (no idea why).