When I said "big difference" I meant there is a definite difference in the overall way the truck handles. I had an 11' Northland, and currently have an 11' Bigfoot, both very large, very heavy campers. I use a piece of 1/2" rubber in the bed of the truck. With the happijacs the camper would always slide around, even on the rubber. In Montana we have some pretty bad winds. A 50mph crosswind is actually not that uncommon. That kind of wind would push the camper around in the bed, plus the bed and all would really twist making the camper lean quite abit with the wind. I also bent my rear bumper due to this "twisting" and I'm sure I didn't do my camper any good. When I bought my new Bigfoot they told me I HAD to have frame mounted tiedowns. The new camper, which is bigger and heavier still, has never moved in the bed. And when I get in the strong crosswinds there isn't near as much flex. Also the old way always "squeaked" as if something were giving somewhere (I guess it was). The new set up is rock solid and much quieter.
Jerry