Well, I've been looking around, the best I've found so far is Blab and prochatrooms.
It looks like the Blab! pro version supports multiple rooms, but haven't seen it in action to learn if refreshes the page or not on changing room
phpfreechat looks promising as well, but can't figure out the new 2.x system to setup multiple rooms. support for it seems limited.
prochatrooms has promise as well. But I believe it actually refreshes the page when you change rooms.
Also found X7chat, which is ok as well. just not sure how to modify and theme it yet.