I have a neighbor with the 7.3 in a 3/4 ton. He likes it a lot. Fuel mileage isn't noticeably worse than the 6.2 and by all accounts it is a pulling machine coming close to Fords diesel engines.
I'm currently driving a 2014 F150 4X4 Supercrew and am strongly considering a F250 next time around. I don't need the ability to tow or haul anything my current truck won't handle, but having the option in the future won't hurt. I could be happy with the 6.2 with 3.73 gears and used F250's so equipped are usually cheaper than F150's.
I have 33" E rated tires on my 1/2 ton and with that combo I get no better fuel mileage than I'd get with the 6.2 and the same tires that come from the factory on 3/4 tons. I'm not really seeing any negatives for me to go up to a 3/4 ton.
