FWIW, the guy behind mibbit.com has a partial solution to the 'stateful server' problem for IRC. In some ways though it's not a problem: it keeps things more informal. I think the ideal thing might be to get a little bit of history when you join.

The reputation thing is both a positive and a negative. It's going to be a barrier to entry for some people - both good apples and bad. Hard to know the ratio...

The interface is nice, but I like my IRC client too.