I'd imagine that the engines will be the same as current. The 6.2L and 6.7 are new. All the ones in our fleet are still flawless, and stupid powerful.
But you can feel both engine ECM's say "ok, that's enough" if you try to drive like a momo. My 6.2 feels like it has 450 horsepower with a trailer, but if I unhitch and do a couple drag launches, you can feel it dial back the power and say, "Nope, you're going fast enough." But for all practical purposes, they're both a bit of overkill in the power department.
The 1-2 shift at full throttle in towing mode is pretty violent. Truck won't last long if you do that too often.
I think GM's are ugly. Square wells, round tires and such. Look like a pregnant guppy, or like an overweight dashund dog. Then there's the DPF tank 4" of the ground.
Plus they don't have any tall customers apparently, my knees go right into the dash on the passenger side.