i actually got referred to line-x by my dealer. he said, for the price the line-x was a better product than the factory applied spray-in option.
cost was pretty close to the factory option, but the line-x was thicker than the factory coat. i have no way of verifying that, but i've been happy w/ my line-x so far.
i've heard that there is a small difference in texture between the two, but i've not done any research to confirm this.
i use my truck like a truck and have not had any issues with it cracking or fading. i've hauled engines, transmissions, sheets of wood/drywall, ladders, paint, tables, furniture, etc. only thing i have is a knick in the bedliner on the tailgate from an engine that slipped and landed there. i'll have to go and get that repaired one of these days... glad i got it.