I've heard lots of people say "my pit bull would never hurt anyone". I have NEVER heard anyone say "my pit bull would hurt someone".
In other words, pit bull owners are either 1) liars or 2) ignorant.
I applaud Delta on this move! ^
If attack dogs are going to be allowed on a plane, in all fairness, everyone else should be allowed to bring a gun on the plane as well. Then it's a fair fight.