How can I move my installation to a different domain or host?
Backup the existing database and server files. Copy them to the new domain/server and update the library/config.phpfile with the new database details as required. It may be necessary to set permissions for the data and internal_datadirectories to world writeable (CHMOD 0777). Lastly, update the Board URL in the ACP -> Options -> Basic Board Information, if it has changed.
Note that if you are moving to a different type of web server and have Friendly URLs enabled, you will need to make the appropriate changes. Refer to the Friendly URLs section of the XenForo Manual for more details.
It's a simple change then, just follow the instructions above.
It isn't necessary to run two installations simultaneously during the change.
Just make the change and point the old domain to the new one so visitors to the old site are redirected, if you still have control of it.
I'm gonna move my www.The8thLegion.com site over to www.BlackGamer.net since I don't care about copyright tutorials anymore. Reading this thread has been a big help. Will be using this tomorrow as I move the site over. I already have two xenforo licenses for both sites.