Good points all about weights.
However there is more to the story. In doing extensive research, I ran across www.safetyhitch.com which is a big time game changer. The real issue folks should worry about is not really what their truck will be able to accelerate to highway speed with, but instead concentrate on what their truck will do in terms of stopping power. A secondary issue is the amount of weight in the pickup bed, which under heavy braking causes the front wheels to lose traction/contact with the tarmac.
In 2008, the game changed when the automated safety hitch was invented. There is no real difference in towing ability between a 3/4 ton truck and massive dually equipped. The only value the dually has is an extra set of tires. The Safety Hitch does that and more, by providing a steerable (at low speeds) axle with better brakes than your truck is likely to come with. The biggest advantage is that your front end stays fully loaded, even under hard braking, giving you vastly superior braking and steering. At high speeds, the steerable axle locks up and provides a longer wheelbase to prevent fishtailing. Even a 3/4 ton will now have the capacity for up to 26.000 #s without a commercial license and actually more.
