Here is the deal with the 6.0. Any good tuner (person writing your tunes) is not going to give you a tune that is going to tear up your truck. There are trucks all over the place running 400-420 rwhp with 750-800 rwtq all day long without problems.
Yes the 6.0 is known to blow head gaskets. This is why it happens. The Ford Gold coolant contains silicates. The silicates are not able to handle high EGT's generated by a good load or relatively high boost when they run through the EGR cooler. They break down into a gell like sludge and fall out of suspension. This crud gets caught up in the tiny coolant passageways of the oil cooler. As the cooler clogs up it restricts coolant flow to the egr cooler. Now the egr cooler doesn't have enough coolant to carry off the heat generated by high EGT's. The limited amount of coolant in the egr cooler flash boils causing high pressure in the cooling system and the truck pukes coolant from the degass bottle due to the pressure. (it has to go somewhere)
Your uninformed Powerstroke owner is not monitoring his coolant temps and oil temps so he doesn't know whats going on and he keeps driving it this way. The problem gets worse, the pressure causes the egr cooler to rupture. Now the egr cooler is leaking coolant into the intake manifold which then runs into the cylinders. Again the high combustion temps cause the coolant to vaporize. This causes unacceptably high cylinder pressure, the TTY head bolts stretch due to the add'l pressure and there go your head gaskets.
Ok now you know the problem. Here's the cure. Get a good engine monitoring solution like the Edge Insight so that you can monitor your ECT and EOT. If those temps get more than 15* apart with normal cruising when at normal operating temperature your oil cooler is clogging up. Rebuild it now to prevent all that down stream damage from occurring. Flush that Ford Gold coolant crap out of your engine with a couple bottles of Restore. This is made specifically to clean out that silicate residue. Now refill it with a silicate free Cat EC-1 rated ELC coolant. This removes the silicates that clog the oil cooler from the equation. If you live in an area where you don't have smog inspections delete the egr system. If you can't delete it replace the egr cooler with the cooler manufactured by Bulletproof Diesel. This is vastly superior to the Ford oem egr cooler and it will not fail on you. If you find that you need to replace head gaskets replace the TTY head bolts with ARP studs and use black onyx (Victor Reinz) head gaskets. If you have to replace the egr cooler always replace the oil cooler. That is the source of the problem.
Now that you have addressed the common problems that scare the he11 out of people, get an SCT tuner (i like the X3) and install some custom tunes and drive the heck out of it. DO NOT baby it. The Powerstroke hates this and will rebel with turbo issues.
Turbo issues are also common repair points with the 6.0. People like to complain that it's because the VGT turbos are pieces of junk. This is not so. The VGT vanes in the turbo need to be exercised regularly. This means making them go through their full range of motion. So put your foot in it regularly and let it see some full boost runs. That will keep your VGT vanes from getting all sooted up and freezing up because of the soot. Again, that is what happens when you baby it. Put your foot in it and you will have less problems. Lay out of it and try to milk it for mileage like you would a gasser and you're going to have turbo issues. Don't let it sit either. That is also the kiss of death to the turbo. The unison ring rusts up and again you have turbo problems. So now that you know you need to give your turbo a regular work out to keep it happy, give it a proper cool down as well. Just whipping into your parking place and shutting it down will lead to coking the bearings and again major turbo issues. Running a good synthetic oil will help here immensely because it handles heat so much better and resists coking. But always let your turbo have time to cool down. This is one of the reasons you need a Pyrometer (EGT gauge). Let the EGT come down to 350* before shutting your truck off. This only takes a couple of minutes, especially if you take it easy on it for the last couple minutes of your trip. If this is too much hassle for you get a turbo timer that will automatically delay shutdown when you turn off the key to allow the turbo to cool down.
Injectors. Ford's HEUI injection system fires the injectors with High Pressure Oil, to the tune of 4,000psi at Wide Open Throttle. Maintenance is critical here so you can not let your oil maintenance slide like you can on a gasser. It will kill your injectors. The injectors also are known to suffer from something that we call stiction. That is when the oil side plunger of the injector hangs up or sticks when cold until the truck warms up. I believe this is caused by varnish buildup that is common to dino oils, especially those containing paraffin. Using a good synthetic oil will take care of that because it actually cleans the engine as it lubricates. If you do find yourself with some injector stiction add a couple of bottles of Rev-X to your oil. It has cleared up 99.9% of the trucks it has been used on. 2 bottles run around $70. A new injector is about $250-$290. Be anal about keeping your oil clean and fresh and changing your fuel filters regularly. The other thing that kills injectors is low fuel pressure. The fuel pressure needs to stay above 45psi at all times and is typically set around 52 psi from the factory. Well the factory fuel pressure regulator spring is weak and looses it's tension over time and can't maintain adequate fuel pressure. There is an updated rebuild kit that uses a better, stronger spring. Installing this spring will bring your fuel pressure up to about 62 psi and solve that. Get a fuel pressure gauge. It's important.
So that covers the frequent complaints with the 6.0. They are all well known at this point as are the solutions. Does it suck we have to fix Ford's blunders? Heck yes it does. But again we know how and once done you will have a very reliable robust truck that is well worth the effort. So address the issues as you can and enjoy your truck. It is a dynamite vehicle. I love mine.