What is the largest cost of vehicle ownership? Depreciation, it is not even close.
A economically rational person does not buy a truck based on fuel economy. Primary considerations should be initial purchase price, depreciation, financing, expected maintenance/repairs, and tax incentives. True cost to own is almost always lower for a gas-guzzling truck than a diesel-sipping truck.
Rationally, if you want the best off road truck with the best MPG/range, massive aftermarket support, and the best resale you should wait six months and buy the diesel JT Rubicon when it comes out.