Yesterday and today I’ve made a few tests. Sorry if I caused some disruption.
Result of the tests are:
Updates
I can now upgrade the server without causing any disruption. This is nice!
I will however show you a dialog window telling you about the new version. You can then decide to reload the client now or later.
Backup restore
Database backups are made every 30min, and they are then stored on another server.
I can now restore to a backup, live, without you loosing your session.
Disruptions? Yes, well. You would notice a lot of things suddenly changing; the room you and others are in, your appearance, the idle status, who you were looking at, etc.
But the game just goes on (from that previous state).
Is this cool? Yes, it is. Hopefully some of you can appreciate the awesomeness being able to restore the backed up state of a real-time game without losing connections. 
Best regards,
Accipiter