I have a 94 2500 8,800 GVWR, 5.9, NV4500, with 4.10 gears.
I personally have no problems with it towing. It will pull 75 in 5th as long as it's not a super steep incline on the highway, then I down shift into 4th and can accelerate just fine.
I would not be happy with a 1500, a 6,000 GVWR 2500, or anything with an automatic. 3.55 gears with my setup was bearable, but not ideal for the speed in which I tow.
Depending on headwind and speed I get from 9-12.5 while towing my Jeep. Unloaded in the city I get from 8-12 depending on how retarded I drive. Unloaded on the highway I have seen 15 max.
I really like my truck and Dodges in general. I hate the fact that they rust so bad, and the steering leaves something to be desired.