First of all, I live in KS where we have all four seasons with vengance - hot, humid summer, and bitterly cold winters with lots of salt and other chemicals on the roads to melt snow & ice. My experience with factory powder coat (PC) is that it sucks - any chip, scratch or other flaw, even sharp inside corners where angles meet, provides a point where moisture enters, and rust forms between the PC and the base metal, getting worse over time until sheets of PC can be stripped off to reveal active surface rust. The protective skids and rock bumpers on my Jeep have been perfect examples of this process, and are now coated with satin black Rustoleum which can be renewed easily as needed.
My impression, based on KS winters is that PC is a nice "fair weather" coating suitable for regions where the temperature rarely approaches freezing, where road chemicals are unheard of, and where sunny days are much more common than rainy days - i.e. SOCAL and the Gulf Coast states, and not much more. Am I off base? A victim of shoddy PC? I really want to know, as right now my tendency is that a quality paint far exceeds PC, hands down.