If a Windows 8.0 machine is part of an Active Directory Domain, what happens to the user/machine domain registration (user profiles etc). when upgrading to Windows 8.1? Are they maintained, or do you have to re-register with the domain? In this case, is it better to remove the PC from the domain before upgrading?

The reason I ask is we are running a small Active Directory Domain with one Windows 2012 Server and three attached Windows 8.0 PCs and want to avoid as many problems as possible when we upgrade.

Any advice/shared experience would be much appreciated.