I'm leaning towards torque myself. We can trim the airplane for a certain spot along the torque curve but once we load the airplane and increase the power required to maintain speed the trim changes. On takeoff when we are climbing up the torque curve it is noticeable, when we power up and pull to vertical the load is increased and the trim changes. Granted the more we spread out this load the less pronounced the change is. Running a pylon airplane that weighs 6.5 lbs and has a YS 115 14x14 power combo requires a ton of right rudder and slow throttle application to keep straight on takeoff. Once up to full speed and constant torque loading it tracks straight through the course and through turns.