I see what mine does to tree limbs (he's obsessed with sticks). Crazy stuff. He turns them into mulch. I wouldn't leave mine alone with a small child, but I wouldn't leave a cocker spaniel alone with a small child. All dogs are wild animals at heart and you can never be 100% sure with an animal (less with humans lol).
But a pit is a dog just like any other. Good ones. Bad ones. I guess the difference is in the damage they can do. I think all dogs that end up mauling people/dogs always display some sort of warning signs. Many people choose to ignore them.
Edit: I don't think a pit is for everyone. They need a strong leader that can give them tons of exercise. Daily. Mine has also been taught "NILF" (nothing in life's free). You want dinner? You better be sitting. You want me to open that door? Lay down.
If you're considering getting one I would do research but I highly highly recommend giving one a chance. I'm so glad I did because I couldn't imagine life without him. Sorry to ramble but it's something that I'm pretty passionate about these days. I think they get a seriously bad rap for the most part.
Ps. Dude is trying to lay across my keyboard right now. If you're not into having a personal fan club 24/7 don't get one!