You buy a 6.0 GM truck because you want something that will do anything you ask of it and never break, and on the off chance it does break, it doesn't cost much to fix.
The repair costs associated with diesels are astronomical and all of them have emissions and fuel system issues. Yes, you can go faster up a hill with a diesel.
There is a reason that GM sold a ton of 6.0 trucks to corporate fleets and contractors.
The 6.0 is ok not great and does have its drawbacks. Its over 10 year old tech, the 6.2 has better Hp and Torque and better torque band. The only reason I think its around is because its probably cheap to make by now.