In my 15 years of towing 5th wheel trailers, I have never seen so much attension on the hitch of the units. I had 2 Gm's that had the right springs in the back that the truck rode like a caddy onces the trailer was on. I sold the truck after 150,000 Miles on the original shocks. I now have a F250 with reiforced springs in the back and it rides like ****, the tug on my neck is awfull. I went to remove the extra leafs and have a broken original truck ply, so I left the extra leaf to hold it until I can get a new spring, besides it soften the ride. The GM was going down 2" when connected to my 2000 Lbs empty trailer pin weight. I am getting a new 3500RL and will surely have less loaded pin weight then my old trailer has. So the extra leaf will surely disapear and the ride quality will get back to the GM setup I had. I also see airbags installed in the back of trucks, they only loosen the leafs and give you a jerky ride like most 1/2 tons have. Air bags without traction bars allows the differential to move up and down. I believe in the Caddy ride and and the old style solid hitch will serve me well.
I saw a truck with air ride and hitch air Pin and when we was riding around the park you could see the trailer moving up and down, thats not for me. Transports have solid pins and they surely put more miles then I do.