This thread is going so many different places...
Glad that Ford came out with a 7.3 gas - I had a 8.1 GM and thought it was great. I think what I liked most about it was the Alison transmission. As a pair, it was like driving a diesel, without the power or fuel economy. At the time, I had never had a diesel so I thought it had great power and was a great engine combination. However in 2015 I upgraded my truck to a Duramax. What a difference. Of course, it is a newer and a nicer truck, but as far as towing capabilities, up and down hills, etc, no comparison. In addition, fuel savings, less cost for maintenance, and less cost for fuel. Someone said Diesel is more expensive, in the past 6 years, I have seen that diesel is mostly the same or less, seldom more. Fuel economy with a diesel can't even compare to the 8.1 gas, 8 MPG was a good day. My maintenance is less since the dealer offers oil changes for life, so I have only had to do a few fuel filters, and some basic maintenance. The other truck was not too expensive, but sold it because the AC went out and I didn't want to deal with that.
I have 2 trailers, 1 at about 8,000 lbs and 1 at 12,000 lbs. For the 8.1 GM we only had the smaller trailer. It towed perfect, but with the heavier trailer, I'm not sure I would have felt the same way. I guess my point, is you can't compare a tow rig with a small trailer at 8000 lbs and say it will tow a 12000 lb trailer the same way...