Hardy I had an idea for your server. Why don't you make everyone start in the same area with 4 or 5 translocators, one for each act, and like act 2 will require you to have an item that you received after beating act 1, etc, etc. I bet you already thought of this though.
Or you could have everyone start in act 1 and at the end is a translocator to act 2, etc, etc, etc and everyone is bound to the hub which would have translocators to all acts (requiring certain, weightless items to go to certain acts.)