OK, as an owner of an '09 PowerStroke Superduty and a diehard Dodge fan I consider myself to be pretty level headed to answer this question. I love my 6.4L P/S as a work truck, it's the most reliable diesel hauler I've driven... but it's not a cummins
You say you will not be doing any reqular or 'serious' towing, if this is the case, then stay away from the diesels; the new diesels with the DPFs NEED to be driven hard and put away wet if you don't tow. As much as I'm a oil-burner lover, it wouldn't be practical for you and you'd run into lots of troubles with the emissions systems clogging up regardless of make.
I would recommend the gas engine in a 3/4 ton, and if you want some good power for the occasional hauling... STAY AWAY FROM THE FORD! The ford's gas engine has zero guts, even the NEW ford built motor is lacking in the 3/4 ton. I drive a '10 F-250 Superduty gas job for my current contract (client supplied
, and with the topper and all my rescue gear in the box (~500lb) the truck is sluggish on climbs, but handles the horrible oilfield roads nicely. The fuel economy is about equal between the gas 3/4 tons, but don't expect miracles, around 13MPG would be average, as they do not have the MDS or any kind of fuel savings management in the 3/4 ton trucks.
If you are set on a 3/4 ton for the heavier duty, then you'll sacrifice the mileage, and I'd highly recommend the hemi as it has much better digging power compared to the ford 5.4L, which is a whimp when it comes to pushing the truck.