As was mentioned above, the Harbaugh family chose to live in SF because of family concerns(better schools/quality of life). They like California better. He just used Miami as leverage as everyone else does.
Face it, the Miami area is not what it used to be. Traffic snarl, high density urban blight, and an out dated football stadium located in a poor neighborhood miles from the ocean.
The team was loaded with average players. SF had the more talented roster. Competing against Belechick probably was a factor too.
Ross would have had to fire Ireland too...and that won't happen until 2014-2015