Not to nit-pick, but worth noting y'all...The OP did ask about 2015 and newer - 2015 is the first year of the Gen2 6.7L, which I have. There are several minor differences, feel free to google them, I don't remember. But, I do know the adaptive cruise+Jake Brake on the Gen2 is awesome!
I also had the trusty crusty 7.3L(mine was a 2001) before moving up. I only ever had one minor problem with my '01. I don't use my truck unless I need a truck, so I'm only using it when hauling, I have a couple other cars for DD's. I'm around 27klbs all loaded up - I can take any mountain pass in Washington at the speed limit, and you can't even hear it working...just set the cruise and go. I have to slow down for corners, not hills.
Problems so far - none what so ever @77k miles.
The power is unbelievable, you'll get slightly better empty mileage, and all the new modern conveniences is great. You won't regret it.
