Normally, when you do a relocate, both servers stay online concurrently, and the various DNS servers begin to redirect the clients from the old to the new one. This takes a couple of hours, and some DNS servers update earlier than others, resulting in the two servers being online simultanously. So if they are compatible, this should not be a real problem, except that then you have connected to the old master, you will not see the games from the new one, and vice versa.
But if the servers are not compatible, this might be a problem. So my guess is that this is the first update for the backend for the next release. t least I dont really see a need for a mainteanance relocate because LFS user and server count have not really been increasing dramatically lately.