Chevy 2004 6.0 vs. 2015 6.0

Well I can chime in, been there and have done it with no regrets. The newer gen 6.0 gives u VVTI, 6 speeds and more Usable TQ (360hp 380TQ). May not seem like much on paper but pulling wise I am much happier. My 02 had 300 hp with 360 TQ (00-07 models same), with 4 speeds, so pulling my current set up was in 3rd. Any hill and was in 2nd. In the new 6 speed both 5th and 6th are OD. I lock out 6th and pull in OD 5th in florida all day long. Most hills here no problem with 5th. One in particular I run it in 4th but still keep 65 at 32-3500 rpm. I do have 3:73 gears so the 4:10 option would be better in other states. I have no issues pulling with the 6.0, I love the 6 speed....it keeps the engine in the right power band. When I leave it in 4th the on i75 it has very little speed lose on any hill here. I get better mpgs not pulling compared to the older truck. I have pulled with gas and diesel and have preferred gas for personal reasons. Am I happy ? Yes.. I have no regrets going to the newer truck. I was in the same situation and pondered the same question that u had. I spoke to so many owners on both sides of the issue. I have constantly heard that the newer 6.0 is better in many ways from the owners, so I chose that route. U still need to give it some throttle at times... But it really moves easier then my old one has.hope this helps.
Kris