I'm always amazed when folks want to give the government the power to ban someone else's dog breed. Two things generally happen when you give government folks power:
1. They screw it up (who decides what's a pitbull and what isn't? What about a pit/lab mix? What about other breeds that kinda sorta look like pits? What if the knucklehead bureaucrat in charge thinks your dog look like a pit?)
2.They grow their power. Pitbulls today, Rotts, Dobermanns, German Shepherds tomorrow. Then it's hunting dogs (because hunting is evil). Then it's all pet dogs (because owning animals is immoral).
Every problem doesn't require legislation to solve. More often than not, the legislation just creates new problems.