The nice thing about these engines is that allot of the issues with the 6.0 were addressed in the design of the 6.4, so they can take allot of abuse in regards to power. Maintenance is key though on these engines if you want them to last, especially draining the water separator.

I've heard of stock trucks well into the 200K+ range as well as tuned trucks in the high mileage range. You can go with DPF OFF or ON tuning, the favored tuning allows it to breathe better and removes the emissions components but there's no guarantee that it will run longer then any other truck out there. In theory it should, but you never know.

When users have added the huge HP tuning mods, the weak link appears to be the trans rather then the engine.