I could be talking bollocks here, but the stiffener is more likely more of a panel-breaker than a structural member...as these doors are sold on their light-weight qualities then I cant see them laminating in a solid steel bar, but I can see them bonding in a strip of wood, foam or even rope as a stiffener. If it was a steel bar, relatively unsupported at each end, worst case scenario in a side impact would be one end of the bar being pushed in toward the driver or passenger. Dramatic, but possible. I'd go as far as saying the door would be safer if the stiffener WAS a bit of rope. They do look scrotum-clenchingly gorgeous though.