One more
for the Undercover. I also have the Bedrug, so I get a little bit of a seal at the tailgate. No dirt or water has ever made its way into the bed of my truck.
Drawbacks:
1) Same as above, two person removal, but very simple.
2) Can't (not supposed to) drive with the cover in the up position, so you can carry a large item.
3) Even though new ones come with a triple LED light, they should offer an optional "good" light setup.
SL