The LineX is definitely tough. But mine has faded to a dull black or dark grey anywhere the sun is on it, and this in less than 2 years. Under the rails in the shade, still glossy. LineX knows it happens, as their warrantee excludes fading. Maybe your truck was parked in the shade? or the camper kept on it most of the time?
I guess my biggest problem with the LineX is no dent protection. If you get "help" at Home Depot and they throw a 4 x 6 in there, it will dent. A PE drop in liner prevents this to some extent. Still thinking about which way to go.