Alot of games use that system, most of them make it possible to change anytime as long you are grouped even if the zones is flagged full. It works but i don't like this system, I prefer a good stable server community like all the good old games...

Sure a system to group up with friends via friendlist like Blizzard introduced it with RealID would be cool but Serverjumping all the time is a bad Idea. And I doubt it will be possible at least now, they working on a server structure for the regional servers they can't just change that in a few weeks.