Originally posted by Shadow:

I would wait personally. Unless you feel like testing and giving them feedback and don't mind spoilers or getting burned out on it for a test server that you won't keep progress with anyhow.

Yes if you play on your friend's test server (or anyone else' test server) and he or she deletes it, sure you'll lose your progress, and that doesn't matter if you have the update or not. But why would you do that? Just use your own computer and keep your progress (or use a common server and don't delete it).