I had one short out on the third rail when it derailed. I prefer the plastic 800 series couplers only because they work better. The new 740 series look great ! and the metal ones are strong !! I just find the plastic boxes with plastic couplers couple and uncouple a lot easier, with the magnets and the pick. However 95% of my couplers are the new 740 series all metal.
Clem