Couldn't you get around this problem, at least to some degree, by splitting the servers as suggested, and have the people in NA work on the EU servers and vice versa? With the help of timezone difference everyone could have better working hours? (Disclaimer: I won't bother with actually working out the times, nor do I know to what extent you need physical access to the servers during maintenance.)

Could it be that people who have joined guilds all are registered to the same server, which means that a lot of the people "on" the servers haven't actually gotten their access yet? Just a thought...