I didn't really want to get drawn into this, but since I started it by posting up what happened this week, here are my thoughts.
I agree with @Sumo that not all breeds are the same and what they were orginally bred for is important in assessing the risk certain dogs pose to people or other animals (although I'm pretty sure this is no longer the case with the British Bulldog...). Unless all dogs with a fighting, hunting and guarding past (Sharpeis, GSDs, Rotts, Dobes, Wheatens, Bull Mastiffs, etc.) are banned, then we are reliant on knowdledge of the breed and traits and responsible ownership, something that is in short supply with all breeds. Anecdotally, I meet far more growling, snappy, aggressive and unfriendly small and furry dogs that I do bull or guardian breeds.
The 1991 DDA is a perfect example poorly thought through knee-jerk legislation drafted by people with no experience of the issue on which they were legislating. They focused on four breeds (only one of which was present in any significant numbers in the UK at the time, and two of which were not thought to be here at all) none of which were recognised by the KC so that there would be no organised resistence and lobbying. I'm not aware of BSL working anywhere and the DDA has not been effective in preventing tragic attacks. People who want status dogs for the wrong reasons will find a way to have them, and move on to another breed if necessary. When I was a kid, Alsations/GSDs were the "devil dogs", then it was Rotts, then Dobes and so it goes. This is what worries me about "exotic" breeds like the XL Bully - bred for looks with very little understanding of temperament, sold to vain people with £5K to spare and no experience of owning and looking after a dog.
I think there should be restrictions and legislation in place, but not the DDA, which determines whether a dog should be destroyed on the basis of a set of measurements, set out in the orginal legislation when no one knew how to properly identify the four breeds concerned. There are countless examples of dogs with no pit in them (and often with a lot of lab) being destroyed under the act. This is not what was intended, is clearly wrong and doesn't protect the public. I'm afraid I don't know what the alternative is, but it shouldn't be impossible for legislators to properly consult and draw up something much better.
I won't gon into too much detail on @Stonehedge 's data above, other than to say that all data on dog bites and attacks is unreliable, not least because most people are incapable of identifying a pit bull properly. The dog in the graphic is certainly not an APBT. The BBC reports of the recent fatality in Liverpool (?) quoted a bystander/witness (presumably an expert, or why else quote them...) as describing the dog as looking like a pit bull or staffy (two very different looking dogs), yet it turned out to be an XL Bully. That said, I'm absolutely sure that pits top the list, as much because of who owns them and why, but I would bet a lot of money that a significant proportion of those 284 were not pits.
Bottom line - different breeds pose different risks (not just because of character, but also because of their physicality), idiots own dogs (no dog, whatever the breed, should be off-lead in public without a reliable recall), risk needs to be managed, the DDA hasn't worked. The fact that I came close to losing a pup that is not one of the four breeds included in the DDA, makes me feel even more strongly about this.
It is worth noting that the DDA goes beyond BSL, yet this tends to be what the police focus on. I would have more faith if I saw more action on dog behavior that is also covered by the act.
Over and out.