With IRC it is possible to allow use to other ports to connect (like port 80 and 8080). I believe this was one of the troubles brought up when you guys tried IRC. Some people couldn't use port 6667. The standard port CAN BE CHANGED. I almost thought what we had was built off IRC until I figured out it was its own thing (realchat). IRC even allows for colors in chat, use of the "/me" command. Kick and others. People could make their own channels just like we do with rooms in the current model. Users wouldn't have to learn much at all. Especially with a web client on the site.

Also, the accessibility issue Phreak brought up SHOULD NOT be ignored. Just because you aren't aware of users using screen readers and such, that DOES NOT mean they don't exist. IRC is old enough where these issues have been ironed out. The propriety crap (like realchat and parachat) use propriety plugins like flash and java - which are not as portable as advertised AT ALL, require the creators of the chat interface to iron out these issue. Most of them don't care about users with issues like this. They are meant for sites with "shoutboxes". Not for well maintained and operated sites like this. IRC and similar interfaces have been designed and some are almost as old as email (and are almost as popular), so they have been around long enough and aren't owned by a single organization or company so everyone had a say in what should be included.

Whatever issues you guys had with IRC can be fixed, you wouldn't be close to the first organizations with these issues.