We should be allowed for members to edit are own shouts and delete shouts to help keep the organization on the chat box. It would be easy for staff and members alike if they make a typo or such.
It all depends if there is a chatbox log, I guess.
If there isn't a log, showing the original messages and the edited messages, then this would be a problem, as some people could insult other members, then change their message as if they never said it.
Staff should already be able to edit their own messages, and I'm not sure who else can.
I don't agree that members should be able to delete their shouts, but I somewhat agree on the editing part.
It depends if there is a log, or some other way to see the edit history.