This CDC pub is old, but shows purebred pitbulls to be more likely to be involved in a human fatality than crossbred pit bulls.
http://www.cdc.gov/homeandrecreationalsafety/images/dogbreeds-a.pdf
As I said, I don't have a dog in this fight. I can only speak from personal experience. Data is not too hard to find. I found the following to be interesting and pretty much in line with my thinking, although I'd be very unlikely to own certain breeds - including pit bulls - as long as I have kids around:
Finally, it is imperative to
keep in mind that even if breed-specific bite rates could
be accurately calculated, they do not factor in ownerrelated issues. For example, less responsible owners or
owners who want to foster aggression in their dogs may
be drawn differentially to certain breeds...
...Several interacting factors affect a dog’s propensityto bite, including heredity, sex, early experience,
socialization and training, health (medical and behavioral), reproductive status, quality of ownership and
supervision, and victim behavior. For example, a study
in Denver of medically-attended dog bites in 1991 suggested that male dogs are 6.2 times more likely to bite
than female dogs, sexually intact dogs are 2.6 times
more likely to bite than neutered dogs, and chained
dogs are 2.8 times more likely to bite than unchained
dogs.12 Communities have tried to address the dog bite
problem by focusing on different factors related to biting behavior...
...Although, it is not systematically reported, our
reading of the fatal bite reports indicates that problem
behaviors (of dogs and owners) have preceded attacks in
a great many cases and should be sufficient evidence for
preemptive action. Approaches to decreasing dangerous
dog and owner behaviors are numerous. The potential
importance of strong animal control programs is illustrated by our data; from 1979 through 1998, 24% of
human DBRF were caused by owned dogs (typically
more than 1) that were roaming off the owners’ property. Some deaths might have been averted through more
stringent animal control laws and enforcement (eg, leash
laws, fencing requirements). Although the bite prevention effectiveness of such animal control ordinances and
programs has not been systematically evaluated, freeroaming dogs and dogs with menacing behavior are
problems that need to be addressed even if they do not
bite (eg, causing bicycle or car crashes).
Generic non–breed-specific, dangerous dog laws
can be enacted that place primary responsibility for a
dog’s behavior on the owner, regardless of the dog’s
breed.17 In particular, targeting chronically irresponsible dog owners may be effective.18 If dog owners are
required to assume legal liability for the behavior and
actions of their pets, they may be encouraged to seek
professional help in training and socializing their pets.
Other options include enforcing leash laws and laws
against dog fighting. We noticed in the fatal cases, that
less than one half of 1% of DBRF were caused by
leashed animals off the owners’ property. Subdivisions
and municipalities that outlaw fences or limit fences to
heights insufficient for controlling large dogs may be
increasing the probability of children interacting with
unsupervised dogs
So how much is the breed of the dog and how much is owner ignorance, negligence, and malfeasance? I don't claim to know. I don't think you can write the whole breed off as brutish, but neither can you say there's nothing there regarding the breed.
Bottom line to me is one should carefully choose both the breed and the individual dog, especially when children are around. Owners should also be responsible and make sure their dog is well acclimated to children or take steps to keep the dog and children separated. In any case, proper adult supervision is required whenever dogs and children share a space.