I think what you may be experiencing is the difference between power to weight ratios. The 1500 truck with the V6 still has 285 HP and 305 lb ft of Tq but its power to weight ratio with the same smaller trailer is probably better on paper and faster in the seat of the pants.
Hook the TT to the V6 and the handling and power will probably be noticibly different.
The 3/4 ton may not have much of a drop off between the smaller trailer and the larger. That’s the nature of bigger trucks.
I hope that helps and makes sense.
Thanks!!
Jeremiah