I also want to add that my current dog is a 140lb Bull Mastiff/German Shepherd mix. I adopted her from a friend after my friend realized how big she would likely be.

My dog is now 7 years old and still just acts like a big silly puppy. She's never bit anyone and is even friends with my cats.

However, if I had small children I probably wouldn't have her because I've seen very nice dogs snap many times. Unfortunately, the size of the dog does correlate with the damage they could potentially do. I also make sure she can't bite anyone or other pets if I have to take her out. She loves everyone and everything but any dog can snap under the right circumstances and since we are not dogs coming we cannot read their minds and don't always know what the circumstances are. I wouldn't rule out rescuing a pitbull. All dogs are not the same. I think it's all more an issue of responsible pet owners and knowing your dog the best you can.

Never forget though that accidents can and will still happen, even under the best circumstances.