The 6.0 Only has problems if its not taken care of, OR if a tuner is installed and used HARD without other mods.
We own one, we also have a tuner and i haven't done any other mods (mainly im too lazy to out head studs in), but it doesn't get driven like a sports car.
Ours has 160k on it and there is nothing wrong with it at the moment, we got it with a dieing FICM ($1200), (previous owner let the batteries die)
I love the interior of our 05, NICE leather and all that other good stuff, get one and take care of it, change the oil and ALWAYS use a fuel and oil addative, never let the batteries run low, if they do fully charge them before running the truck, drive it hard every now and again (to clean out the shit in the EGR and turbo).
Despite all the taboo of the 6.0 I say go for it, just don't buy one with problems. because injectors are 1500+ a FICM is 1200+ head gaskets A FUCKING LOT+