Anyone got a 3500 Ram 6.4 Good or Bad?

Hey guys,
I'm contemplating purchasing a new 2017 Ram 3500 Dually with the 6.4, AT, 410 hp and 430lbs of torque. Anyone have one? Yes, NO, Good, Bad? On my 99 Ram diesel, pulling I got around 15 mpg give or take, Im wondering how much less a gas motor would be, 8-10 or so? If anyone knows anyone who has the 6.4 in a truck, please drop me a line or post a reply here. With the price of the new diesel duallys, I'm thinking I can spend less on this truck and just pay more for fuel.... what do you think?
Martin