90% of the trucks at the construction company I work for are the 6.0 powerstroke. We also have a 2001 duramax, two 7.3 powerstrokes, two 2011 powerstrokes and a 2009 powerstroke. And a cummins with the 12valve. Also a handful of vehicles with gas engine but that's not the discussion. Granted they are all construction vehicles and pull heavy loads every day but they are also well maintenanced.
The cummins has 328k miles on it and still goes, but is on its last leg. It will stall the engine if you tap the throttle then let off. It leaks oil and is noisy and gutless.
The duramax had its Allison rebuilt last year at 150k miles (from pulling too much weight daily to park city) and it had its injectors replaced 5 years ago but it was covered in the Chevy 200k/7 year warranty on the leaky injector issue). Also with a duramax you HAVE to replace the fuel filters at their intervals and highly reccomend a dealership fuel filter, if the duramax doesn't get enough fuel flow it will kick it into limp mode and max you out at 1500 RPMs until you turn the key off, remove it from the ignition and open the drivers door (this resets the engines computer and allows you to continue in full power mode.) it usually happens when you are floored with a heavy load and the engine is trying to get more fuel. However we have since switched to OEM fuel filters instead of Napa fuel filters and have not had it go into limp mode ever since.
We have had zero issues with the 2011 and 2009 powerstrokes.
However our 6.0 powerstrokes have ALL had major issues that if any one was my personal vehicle I would be both irate and broke. Anything from replacing injectors because they stick and make the truck run like crap on several trucks to a couple trucks having the EGR cooler go out, dumping coolant into the intake, through the engine and blowing white smoke out the exhaust. We put the EGR delete kit on them from RKL diesel and it makes the check engine light stay on for "insufficient EGR pressure/flow". Also have had issues with diesel fuel in the coolant of a few trucks, had an oil cooler go out on one with 76k miles and pumped engine oil straight into the engine coolant. My work truck (2006 6.0) has had the transmission rebuilt a month ago at 135k miles and is in the shop again now because it went out again last Friday on the way home from Vernal. I don't think I could buy a 6.0 because of my experiences with them at work. But like I said, they all are worked hard daily.
