After owning a DS4 equipped 6.5, I wouldn't trust one as far as I could throw it. The motor itself isn't THAT bad. There are some crankshaft snapping issues and block cracking issues, both of which are likely related. They do have headgasket issues, and the cooling system is barely adequate on early turbo models.
Everyone is so quick to point out the flaws in the 6.x series engines, are the vortec small blocks really any better? Between intake gaskets, headgaskets, cracked heads, junk distributors and injectors, and leaky oil cooler lines I'll probably never own another.
I absolutely love my N/A 6.2. It's a full size 1/2 ton 4x4 pickup that gets 18 mpg or better in town. The mechanical injection is super simple. The cooling system is just fine on the n/a models. It has plenty of torque when I need to pull trailers. All of the issues these engines have are fixable. stainless steel braided AN oil cooler lines, fluidampr, and a new crank pulley is all you really need to do to keep the N/A trucks alive and happy. Plus, I get WAY better mileage than my 6.5 turbo got. The best I ever did was 16 mpg in town, I think a lot of people hype up their mileage, highway mileage was pretty good though.
My vote would be an n/a 6.x engine for simplicity, reliability, and ease of swap. The turbo just complicates things and retracts from the reliability too much for the power increase to be justifiable, IMO. They aren't as gutless as most people make them seem, they feel about like a 305 with a little more torque down low.
