I love coil springs....nice ride, decent handling, and my truck even has good traction in mud and snow with a one legger rear end. I also have fairly large rear tires that help out, lol.
I agree though....coils aren't the best for hauling. My truck will squat down really bad when it is loaded up. It sags an easy inch or two in the back if i put a riding lawn mower or a 4 wheeler in the back, which way ~500 lbs. or less. On a leaf spring truck it won't sag very much at all. But i don't haul heavy loads in my truck very often, it is mainly driven on the street so coils are far better