I love pitbulls. Some of the sweetest dogs I have ever had the pleasure of interacting with were pitbulls. I have only ever been aggressively attacked and bitten by small poorly trained yipyip dogs.
I have been bitten by bigger breed by accidentally stepping on their foot or tail, but I can't hold those dogs responsible for my mistake and their evolutionary response.
I have been around big dogs for most of my life. One thing I will tell you is that any dog will let go of any bite if you shove a finger up it's ass. I have helped some neighbors who had wolf dogs latched onto their arm get released with the ol finger up the ass trick.
Stay safe out there.