My friend just went from a 2004 Ford F250 6.0 to a 2016 Ford F350 6.7 and loves it. Tons more power, better fuel mileage, lots of new creature comforts. I took a ride in it, its very nice. Faster than my Cummins for sure, but I didn't buy a 7500 lbs truck to race...
As has been said, be mindful of the CP4 fuel pump. I believe the CP4 has been redesigned and is less likely to have problems... but I think you need to do your due diligence and make that decision for yourself.
The 2017 with redesigned frame and aluminum body is coming out. Prices will likely increase. New frame is great, some people have concerns about aluminum body. Time will tell. If you are flexible and willing to accept what dealers have on the lot, you can probably find a 2016 with the "old frame" (that was perfectly fine for a long time) and get a good price if a dealer is trying to move old inventory.
He got 20 mph driving down the interstate 800 miles to Florida last week, pretty good for a truck with only a couple thousand miles on it! I'm not sure his towing mileage yet.
My cousin has a 2011 F250 with the 6.7 and abuses the **** out of it and its still holding up great for him. Its a farm truck and his daily driver, lots of abuse, rough roads, long idle, etc and no problems yet.