Well, I tried to offer up some ideas. Maybe they would work better as mod powers (and really, thread-level banning should be a potential mod ability).
So many GMs do thing in so many different ways. At the very least, a Co-GM would be useful for the sake of having someone else able to update the OP posts on all the tabs. That should be the very, very basic role of the Co-GM. That is, if one is employed by a RP at all. The one I ran in the past could have used it for sure, and I know several I participated in that had Co-GMs in name, just ones that were powerless and could have used the OP editing ability.