I gotta say as a dog owner and had friends with staffords, (but not pitbulls), to Alsations and dobermans i am not intimidated by dogs and as mentioned here whilst dogs can be quick and aggressive, you can outwit them fairly easily remember, bigger they are the slower they move.
Key would be to act quick, without hesitation, most dogs can be wrestled down easily. Options to twist neck, gauge eyes, strangle etc, stay in control of the head, unpleasant but if you feel your life is threatened the dog wont reason with you at this point.