It's for the best that he leaves town. I'm sure he can perform well in another city. MiamiFan isn't nearly as vicious as DetroitFan and he'll be playing behind a very established starter in Culpepper. There'll be no pressure on him with the Dolphins...he'll be a serviceable backup but I highly doubt we'll see him be a full-time starter for the rest of his career.
I think Harrington will be fine once he gets outta Detroit. The big fat pepper man will start to grip in Miami and Harrington will take over about mid-season this year.