My husband and I have a rottweiler named Ursa. She's a very gentle female, with a clownish sense of humor and a definite feisty streak: she had a stand off with a black bear in our back yard and won. She's not a big girl, only 70 lbs, but she's a total alpha. Most importantly, she was protecting her pack. After the bear ran off, she slept in my daughter's room, where she felt she was needed most, I'm sure.
She's also in training to be a therapy dog, and will sit for her Canine Good Citizen test shortly. The relationship she has with my three year old daughter is nothing short of magical. And I know she's safe with Ursa in the house.
Now, yes--if a rottweiler or a pit--or a Golden Lab or any dog for that matter-- is raised by a negectful owner, they are capable of great damage. But, to this day, I will avoid all small dogs iff possible. ps-- The Dobies I've met have always impressed me with how good natured and smart they are. (They's just too dang skinny for my taste!) ;-)