Nothing!
I chose the 4.7 v8 in hopes of better fuel mileage. I get around 18 in town and 21 on a long trip. This is 2+ mpg better than the Honda. The 4.7 v8 is very quick and torquey. My brother bought a heavier 2006 Limited with the Hemi and I can tell very little real world difference. Has so much room behind the second seat that it serves as a pick up with a shell cover. I would have preferred a BMW X5 if I could have afforded it, but this truck does so many things well I have changed my mind. It is a vertable Swiss Army knife of a vehicle.
Wait till the auto tranny blows itself up.
I have 54k on my Durango and still running good very reliable.
I am surprised you are getting better gas mileage than the Honda Pilot.
I have a '04 durango with the 5.7 HEMI and I love it. I have 36,000+ miles on it and all I have done is change the oil. The only bad thing was the goodyear tires that were junk I replaced at about 10,000 but very satisfied.