Back in 1981, I was talking with a guy regarding selling one of my bikes, (glad I did not, but thats another story) he was showing me the suspension parts to his Lamborgihini that he just had done as the original paint was not very good. a few years later he had the car apart again as the suspension arms were rusting again. Lamborghini- Italian for kit car.

Powdercoat is Tougher, can take impact abuse much better, but not the panacea for rust prevention.