Hello Jaybro, And Welcome to the org.
I have had my 2005 6.0 for right at a year and I love it. When I bought it, it had a small oil leak at the front crank seal and about 3 months after I got it it started running rough. I took it to the Ford dealer they fixed the leak and re flashed the computer and I haven't had any problems at all. The truck starts up at -12 without plugging it in. If you get the auto trans you will like the way it shifts and when you put it in the tow mode it helps hold the truck back on hills real well. The fuel mileage is not as good as I would like but I got an SCT programmer and it went from 14 to 18 all around driving.
Many people don't like the 6.0 but it seems like most of the 6.0 owners I know love them.
The head bolts seem to be a problem especially if you are putting in some high horse power tunes, they can stretch and you can blow a head gasket. There is however a fix for this, ARP head studs. If the truck has under 100k on it and they blow you can usually get them put in under warranty. You would have to buy the studs and take care of the technician working on your truck. Look through the 6.0 problem section on this site, you will find a ton of information.
Good luck on your decision. I hope my post will help you.