Could you add a splitter and merger that attaches to storage containers directly? It would be awesome to be able to have more inputs/outputs for a container that isn't tied to the speed of your fastest belt.
EDIT: Ooh, while I'm thinking about it, how about splitters and mergers that connect directly to each other? All of this could, I guess, be considered "game breaking" items to some people, so I wouldn't even mind if it was an end game, last item obtained kind of thing. It should just be a thing.