we went from an 04LLY to a 2015. In ten years they made a huge number of improvements in the drivetrain, creature comfort and noise levels. 04 fan would run quite a bit and you KNEW it was running. never overheated, but would kick in on hills. Not so on the 15. 04 went to our son, love the 15. the only things I don't like about the 15 is that it is 2 inches higher off the ground, makes getting in and out more difficult. on the 04 didn't need to use the running boards, on the 15 I do. And the 04 hood was sloped more so it was easier to see directly in front.
And the 15 gets a couple mpg better on the highway non towing than the 04 did. towing and in town is about the same for the 04 and 15.