RBBC is good stuff but it doesn't mean that you don't have a "starter" who's your primary back. Additionally it gives you a chance to find the back with the "hot hand". Believe me when I say that if they start a game out sharing the load and one of them starts busting out then that guys going to be "leading the committee".
It'll be Davis. None of the things that put him in the starters role have changed. The fumbles got inside his head and he needed this time off IMO. He also needs to be used a little less than the Texans were using him. The offense becomes more effective when there isn't a 75% chance that the ball is going to Domanick Davis.
Fitz makes bad decisions. That's not going to change.