All the 6.4 guys talk about is fuel/maint cost vs the option price. Here, FB, it's all the same refrain.
Believe it or not, some people like the raw overkill of the diesel for any task and are willing to pay for it. I have been "over-vehicled" my whole life. The second my 1500 Chevy 5.3 hooked up to that 6,300lb trailer and got its butt kicked by it I was on the way to diesel land. As a lifelong gearhead, I don't like the feeling of a stressed vehicle. Hanging a gasser out over 4,000RPM for minutes at a time to get over a hill is not for me. My diesel is a DD in the 18-18.5mpg area for my work loop and hauls mostly sailboat fuel. I may only tow a few times a year just like you 6.4 guys, but you can have your $9,100. I'll take my 850lb/ft and instant resale.
See ya over at the Ike Gauntlet for one of our "few times a year" pulls.