It's not about bites, all dogs have that propensity. It's about size, strength, attack and not letting go. I would have kept a shovel handy too had I Pits charging my fence. No PET lives in the back yard, sorry, they just don't.
We wouldn't even be able to have our homeowners insurance were we to have a 'sweetheart' animal. If these dogs lose it, they do not bite..........they attack and do not quit.
We've had two huge German Shepards over the years so I'm not afraid of large animals. They lived in our house, not chained in the back yard.