never had the 6.0 so I won't comment on something that I have only heard about.

I do have the 6.4. Solid motor, takes a little getting used to with the emissions but once you understand it there will not be any problems.

The 6.4 is a hwy/towing motor. You need to figure out how you would use the truck before buying this motor. That is what I did. Not a city truck. You can drive in the city and low speeds but eventually you will have problems unless you open it up.

As far as cab off stuff....you can do just about everything with the cab on. Cab off is the preferred method and is faster but if you don't have the facility you can do what is needed.

Maintance is very important on the 6.4 so if you don't like to look under the hood then this is not the motor for you.