Maybe the reason your friends with the lifted trucks don't want a rollpan is because, in all honesty, they don't provide a lot of protection for the rear of your ride.
Another reason could be that to get into the back of a lifted truck it is a little harder without a rear bumper to step on, and get up into the bed of the truck.
Rear bumpers don't look bad, but for the ultimate in the looks department a rollpan is the way to go. Your sure as heck not gonna put a rear bush bumper or tubular bumper on a lowered Dakota though. :nono:
I've got a SS II urathane rear rollpan on my Dakota. I went with the urathane because of the ruggedness of it. Fiberglass rollpans have a tendancy to get holes or "spiders" in the paint from rocks thrown from the rear tires because their not as flexable. It's the same material as your lower front valance below the front bumper.
If you decide on fiberglass, urathane or metal the best thing I can tell you is to "Rockguard" the backside of it to prevent damage from rocks from the rear tires.
Hope this helps you out somewhat on your decision. :huh: