Having survived an attack by a Pit Bull I would be concerned. They can be sweet to their owners but if they feel threatened look out. I was an Avon Rep. and making a delivery and all I did was knock on their door and it shot through the doggy door and attacked me. I have scars of a perfect set of teeth in my arm and hip and I have had post traumatic stress for years. I will never recover mentally from this attack. If the owner hadn't heard my screams I probably wouldn't be here today. The dog was dragging me to the ground when she showed up.
Personally I am pleased that cities are making owning one against the law. I've seen too many headlines in the news of children being attacked and killed. My friend is a vet tech and she also has seen many sad stories.
Animals can be great pets but we have to remember they are biologically programmed to be wild animals. Just look at Siegfried and Roy and how that turned out.
Oh and I forgot to point out that the owners said this was a sweet dog and they had a toddler son. Animals are unpredictable.