There's no doubt that the towing capacity and payload will be superior.
Fuel mileage will not be as good, but I'll wager that it's be darn close, I'd go so far as to say so close that the difference will not amount to much (2-4 mpg at most). The towing capacity and extra power will far outweigh the slight decrease in economy. I also wouldn't be surprised to see it get the same (or better) economy when loaded (same or better than the ecoDiesel Ram, that is). You'll have to put your foot down alot less in the Titan, so that may affect the mileage in the real world.
Fuel mileage will not be as good, but I'll wager that it's be darn close, I'd go so far as to say so close that the difference will not amount to much (2-4 mpg at most). The towing capacity and extra power will far outweigh the slight decrease in economy. I also wouldn't be surprised to see it get the same (or better) economy when loaded (same or better than the ecoDiesel Ram, that is). You'll have to put your foot down alot less in the Titan, so that may affect the mileage in the real world.