I want to make this quick.
My opinion about Closed/Open Alphas and Betas - nonsense. This kind of thing is not for this kind of a project. You should have made that Closed Alpha silent with a few players and then release public release (while not stable, for example Aura Kingdom private server, Ninja Saga. These games came directly to Open Alpha state and were updated from time to tame. Basic structure was tested in so called "Closed Alpha"). Now you are just teasing people. I know you want more fans but releasing server for everyone to come is the best choice.
You should pick lvl caps and use the time to update the game and fix the bugs. The first lvl cap could be lvl 25 or something close to this. You could have this cap for 2 months if you want. People would be happy. You would have enough time to fix stuff. And then you could raise lvl caps by 5 lvls from time to time.
Also, a lot more people would report bugs. Of course it would be harder but your community would grow stronger.