I had a 2008 and it only had 15,000 on it when I traded. That was not because of problems but because I no longer needed that large of truck. I did need to have the radiator replaced under warranty and had no other problems. The need to jack up the cab to do any major work was always a worry to me but having never the need, it was only that. The mileage while pulling was usually 7 to 9MPH depending on how heavy my foot was on that trip or how hard the wind was blowing. Without the load I usually got around 12MPH. In town or on the highway. I liked to drive the F450 better than I did the 350. They had tightened up the steering radius so you didn't need 40 acres to turn. The 6.4 was quite a bit quieter than the 6.0 and a lot quieter than the Cummings the dodge uses, although I would prefer the Cummings!
At the time I bought the Ford it was the only pickup rated to pull as much as it did. I know that the competition has responded by upping the pulling power as well.