I only have about 4000 miles on mine, I've only driven it real hard once and I haven't hooked my 5th wheel to it yet. It shifts good and almost always use the low speed governor to start from a stand still. I don't have any issues with it.
I just got back from a trip to Seattle (370 miles) mostly at 70 mph and got 18. 6 mpg. Last weekend I went to Hoods Cannel, about the same miles, and got 20. 5mpg, mostly at 55-60. The overhead is a lot more optimistic, by about 4 mpg, the the pocket calc.
Dave