For me one of the main issues I have with american locks is the key retention part of it I often will close the shackle and the way it looks I rotate it the wrong way back to closed and end up with my pins in the bottom. and I still haven't figured out how to sort that out without destroying the lock.
I have never successfully BOK picked an american. The thick Peterson pry bar can sometimes if the lock is turned at an angle provide enough tension with its weight to pick open the lock and my finger is only there to keep it in place. I have experienced this on enough of the ones I have to not feel that it was lucky.