A recent thread on Rennlist OT dealt with attacks of pitbulls on humans. Included was a video:
LiveLeak.com - Pitbull attack in Curitiba - Brazil - Warning: Graphic.
This video is NSFW, or home for that matter. And one could only assume, from the video, that in the environment that the pitbull was raised, disastrous results could be expected.
Bottom line, for me, is that I wouldn't let a pitbull on my property. And I wouldn't rule out other breeds in that respect. We had a GSD, and toy poodle at the same time, when we were younger, and were raising children at the time. Both were great dogs and affectionate with the kids. Occasionally the toy poodle was protective of the kids. The GSD was too lazy to accomplish that task.