I work for a small-city pound at the moment. We get a variety of dogs in, but a very large number are pits because this is the type of city (i.e. a city filled with meth-heads) that attracts people who want pits BECAUSE of the conception that they're "mean" dogs. The only breed we get more than pits are labs and lab mixes and that's because labs are EVERYWHERE. I've never met a pit that was a constant danger to me, personally, but you just need to look at them to see how much biting force they have. I am, typically, the one that handles the dogs. I take them out of their kennels and take their photo, I feed them and water them, take them in and out to visit people, but virtually every full-blood pit that I've dealt with has been animal-aggressive (unless it's a dog they've grown up with). They are fiercely territorial, and we have had calls multiple times about pits chasing people down because the person had passed the dog's property. We quarantine dogs that bite people and out of the year that I've worked there and, maybe, thirty to forty dog-bites (I can't recall the exact number at the moment), a majority of them were labs, not pits. (But, again, it's because we have so many labs). Just last week an Australian Shepherd took a chunk out of a 6-year-old's face a quarter of an inch deep.
When I first started my job, there was this huge silver pit named Psycho. To this day, he is the biggest pit I've ever seen. His head was broad like a dinner plate. He's the first dog I had to handle, and as I fed him, he broke his way out... because he was so excited to eat. He promptly went back into his cage when I put his food dish in there. One of the scariest looking dogs, but so sweet. (My favorite dog was a mastiff-pit mix named Bruno. He was the absolute sweetest dog. ...and huge.)
There are dogs that are bred as your "typical" family pets (like labs), there are dogs that are bred for hunting (like hounds), there are dogs that are bred for protection (like pits and rotts) but not all dogs have the same personality. The breed does not STRICTLY make the dog. I don't dislike pits. I wouldn't want one because they typically are animal-aggressive and can be violently territorial, but in a typical setting, they don't really hurt people anymore than any other dog can. So, I am not anti-pit, but I do not agree with the uber-pro-pit notion that they are passive-sweet-as-can-be-and-it's-all-only-a-bad-rap-because-when-I-was-five-we-had-THE-sweetest-pit-and-it-never-would-hurt-anyone-etc.-etc.-etc. because I deal with pits on a daily basis and I have seen them attempt to fight dogs through the kennels and they have bit people and dogs and have chased down passerbys. (Again, not all of them.) BUT all dogs are barely tame animals. I think the meanest breed I've dealt with are chihuahuas. I'm not kidding. They're EVIL.
I'M NOT A DOG EXPERT, but I have picked up a lot in my job. You can PM me if you want, but I'd like to know what's going on before I start giving out my opinion. ;)