I have them. I'm near the end of their life, and am looking at either 19.5's or, dare I say it, a 2017 F450 that comes with 19.5's.
I haul a VERY heavy TC + a 10k Wells Cargo trailer. only ever had one incident where lack of traction made me pucker, but I was able to still control it and get through. Coming down a steep, icy campground driveway here in Leavenworth WA. I was able to work the trailer brakes and keep it straight. Overall, these have been good tires. One did have a side-wall bubble bulge develop, and was replaced under warranty no questions asked at Discount Tire.
Overall, I would recommend them. I almost exclusively boondock, these have had good mud/snow/sand traction, I have never gotten stuck, empty or loaded. Ever.