Even if I am a Hoster, I have been an alpha/beta tester of games before. I see more value in helping to test the plugins, than to keep the old world. However, it would also mean it messes up with out Halloween event we have been planning directly after we finished the beach party.
On the other hand, the faster we have an updated server, the faster we can have events up again, with rewards and all. That in itself, could be worth it. Also, the faster we have a newer server up, the earlier people come back. I am at a twofold right now, with slightly leaning to the test server.
Maybe another option could be, a secondary server for those willing to test things out?