The 3500 has many differences from the 2500 including brakes, axles, springs, shocks, cooling and frame.
I was much happier with my 3500 longbed dually crewcab than I was with my 2500 srw single cab. The ride towing felt similar to a luxury car. Empty the 2500 and 3500 were similar ride quality.
Longbed Duallies provide a very stable ride when towing. Shortbed ride can be choppy depending on the roadway especially if the road is built in sections. If the sections are just the right length and your speed is right it will create a porpoising action that feels like a bad amusement ride.