So rooms are "global" between whatever hosts your host happens to know about? So it's one giant netsplit party forever and only your server admin can ban someone?
That doesn't answer the question.
How are you resolving things like... user name collisions when the servers reconnect?
With Parley, where anyone can bring their own instance, and they are not guaranteed to not to be malicious, that could be an interesting issue to solve.
Although it must wreak havoc on many IRC clients, since the @ sign has a very specific meaning in the IRC protocol. :)