I had a pair installed on my Silverado for three to four years before they began to crack/break. Removed them. No rust, Texas truck though. Upon removal they do tend to scuff the paint in a few years. Guessing this is from the side portions that overlap the bed not having adhesive strips, moving slightly when placing or loading stuff into the bed using the rail.
Alternative? Have the bed rails sprayed. Had mine sprayed to mimic the outline of the plastic rail covers.
Picture of sprayed rails. Can't remember if it was sprayed in Rhino or Line-X.