Well,I have a 2003 HD 2500/6.0 sitting in the driveway along side my 2008 Ford F-150 Super crew and have pulled my trailer which is around 8k and a wood trailer that runs right at 10k(mobile home frame) with both and I can tell you my son or myself can't see much of a difference between the two in any way towing other than the Ford has a better power band for the hills.
We also pull the other two,22 and 24 ft travel trailers with both rigs without bars or sway control with out seeing any difference to speak of.
Now if I was going to put a cab over camper on, the 2500 would get the nod but not towing so far.
Just sold a 3/4 ton '76 Ford with a 8.5 Lance on it that didn't even come close to towing as well as the Supercrew, power or handling. So no, in my experience the 3/4 ton does not always tow better.