One thing that JB has working against him in Miami is that he was the pick of the previous regime. They passed on what many feel was a sure fire first round, all-pro lock in the first round to take Beck. They are looking to disassociate the themselves from any remnants of that squad.
In reality, Henne is no better than Beck, but will be given the benefit of the doubt because he is the new regime's choice. I still think that the best place for him to be is Carolina. Good receivers, good line, good defense, decent running game. All they need is a QB that can get the ball to the receivers and stay healthy.