Gary,
This subject has been beat to death several times, and there are opinions on both sides. My experience is that in climates with harsh winters and chemical melts on roads powder coating is a bad idea - it is not flexible like paint, and if there is any flaw the metal will rust madly beneath the powder and you don't know it until the damage is severe. Others show pictures of powder that was put on over the road trucks, and still looks good years later. I've come to believe that the biggest problem with poor powder is poor preparation, just like paint. Bottom line, powder coating is a type of paint, but due to the application method it is a rigid coating and it does not like flex at joints. Here's a link to a very quick search using "powder coating" as the subject: http://www.clubhotrod.com/search.php?searchid=233515