I don't think I would sink $10k into an '05 truck, no matter what brand or what engine. And I love my 6.0 too. Even so it wouldn't make financial sense to me.
But for the OP, I'm reading between the lines and thinking you don't really know what, if anything, is wrong with your truck. You're just reading all the scary stuff on the internet. It might be that you need a dose of reality.
Getting the scangage and learning how to use it to diagnose your truck is a good start.
Staying far away from any Ford dealer is your second step. That's where $6-$10k quotes come from. It will take some research, but you need to find the real experts in your area on the 6.0. Reach out to places like the state chapters over at ford-trucks.com forums, and they can tell you who to trust.
Hate to say it, but most of the scary stuff comes from dealerships that have high shop rates and don't treat their techs well. The good ones don't stay at dealerships.
You are probably looking at more like a tops of $5k to fix any issues with your 6.0. Chances are you are looking at oil/egr coolers, and high pressure oil leaks. Those two things done together I could get done for about $3k at a trusted shop in my area. Maybe some injectors and those get expensive. They are also commonly misdiagnosed. Don't be talked into doing head studs preventively. It might never need them.