mine were cheap to acquire, easy to make (had to farm out the welding) and I've dropped the truck on them a few times now and the results were nothing more than scratches. :D
on the subject of attaching to the rockers, mine don't exist so that wasn't an option. but if I had pristine, structurally sound rockers, there's no way in hell I'd be punching holes in them. but then, I live in the rust belt so that skews my view of things... :(