For those interested, I did some towing with the the Canyon Diesel one was my 16 Cargo Trailer I also towed my 492v back from storage at Lake Amistad.
At no time did I feel unsafe or that the truck under performed. Whith my boat mileage on the low side was 13mpg at 80mph (I typically only tow at 70mph 80 was see capabilty) once a stayed closer to 70mph it was 14.5mpg after filling up and hand figuring. My 6.7 Cummins 3500 Dually at best gets 16.5 mpg towing my boat. The exhaust brake worked well and had plenty of holding power on downgrades. The only issue seems to be the intergrated brake control, I am taking it to dealer tomorrow for them to check out (it seems to not be working properly). I only towed my cargo trailer about 20 miles just for kicks. For obviuos reasons as far as width goes I will add some mirror extenstions if I will be towing the cargo trailer more with the Canyon.
The truck held speed well and droped 1 to 2 mph on inclines and once the down shift occured went right back to the set cruise control speed. As expected the high end punch is less for obvious reasons from bigger diesels. However overtaking another vehicle from 65mph towing my boat was not an issue. It rode well and the suspension was solid the truck has plenty of stopping power. I have no doubt it can handle its max towing capacity both pulling and stopping.

I took a friend with me to Amistad and by the end of the trip he kept saying how supprised he was with the truck.

All in all, time will tell how I will like the truck. But so far its good. The only thing I will change to my previous posts is that I would use the Canyon Diesel to tow my boat anywhere I wanted to go no matter the distance.