Pay @ the Pump sucks, it is faster to go to the clerk even if there are a couple people ahead of you. Pay @ the pump is not controlled by the clerk usually, so if something goes wrong your standing there waiting for something to work that the clerk is not even aware of having failed.
Just pay inside.. Especially when its cold. Why the fuck would you stand outside for three minutes trying to pay at the pump. One moment please, one moment please etc etc.