Ashnic,
Do you know how much your trailer tongue weight is, loaded up and ready to go? What all do you carry in the bed of the truck: coolers, firewood, etc? Do you have/like truck toppers/caps for the bed? Total weight of passengers? All this add towards the allowable payload capacity of the truck.
We just traded in a '10 Chevy 1500 4x4 ccsb 5.3/6spd/3.42 combo on a '13 2500HD. Main reason- tw of about 900lbs, truck cap which was about 200lbs, we were just over the trucks gvwr, but under awr's, And my wife wanted the coolers and firewood (when we take it) out of the trailer and in the bed of the truck to make set up/teardown easier!
Old truck payload capacity was 1550lbs, new truck is 2750lbs.
As for difference towing- our maiden voyage with the new beast is this w/e! So time will tell!!!
As for how some think a 2500 is a lot bigger than a 1500, I think it has to do with the height of the vehicle! Now granted, we don't drive the 2500HD every day,only have about 900 miles since we bought it due to a trip to the Great Wolf Lodge, then Kalahari just to get some miles on the truck before this w/e camping trip. But going from my every day driver Cobalt to the truck is a huge difference!
Good luck deciding!
Chris