I am not aware of the 4.10 being an option for the V10, I thought it was the 3.73 or the 4.30.
A friend of mine has an F250 V10 with the 3.73 rears and I think 10mpg unloaded mixed driving is the best he has ever seen. I know when he is towing his little 5th wheel all I hear is about the gas milage being the 5-6mpg range and lower if we head into the blue ridge. Its his most common excuse if he does not want to go camping with me is how much gas costs.
I know my 2006 F350 6.0 gets around 16 highway, 12 mixed when unloaded, and 10.5 pulling the sanibel (at least that was what I hand calculated going to FL and back in various wind conditions.) I am satisfied with it and not looking at a 6.4L. I would move to a 6.7 if the deal was right, I drive one regularly for my PT job and its a smooth powerful motor. But out of the 6.4s that job has all I hear about is issues with the DPF filter.