I had the second one for years on a Line-X'ed crew cab. It's a really nice piece. I could travel in the truck with my family with luggage in the bed and not worry about rain but when I needed to haul something larger the cover comes on and off easily with no tools and takes less than a minute.
Pretty good run-on sentence, eh?
And as you already know, the the frame mounts under the rail and is no-drill. It worked for me.