Hmm if you are getting cupping, it's something specific to your configuration. You're running too low pressure, or low pressure for how much you're carrying, or you have an alignment problem.
I'm not a Goodyear fanboy. Frankly I think they are a overhyped as a tire company. They spend a lot of money on advertising and it gives them the illusion of being the leader. Toyo, BFG, MT, and others make as good or better tires in general. With that said, the Duratrac is an amazing tire. I've run it on a few of my trucks...although the last 2 trucks I've had I've done Toyo OC AT2's and AT3's. I would have done Toyos if they came in 295/65r18. But the Duratrac OG is considered a MT, but it rides like an RT, and it's as good in the winter as any AT. I think it's the best tire they make by a country mile. The RT version's lugs are a little closer together. It seems more like a traditional RT. But it rides like any AT, possibly better than my Toyo's I just came from. I haven't been through a (Minnesota+North Dakota) winter with them yet, and the offroading I've done with them wasn't too intense yet. Time will tell if the RT is as good. I hope so. In regards to the original Duratrac, you're doing other truck guys a disservice if you are spreading bad information about a great tire.