Just out of curiosity, are you making that assumption based on that incident? If so, I'm not saying you are wrong, but I do think you need a more controlled set of experiments to support your statement. Personally, I think you were lucky with the dwarf bite. I have seen spec. caimans rip into things (such as a glove) with the intent of causing as much injury as possible - witnessed by holding on and violently shaking back and forth before releasing. I wouldn't want my hand in there!