Ben,

I don't know all the aerodynamics terminology but understand the steady state balance picture. I apologize for being an electrical engineer. In the terminal velocity situation the applied force is m*g so the mass stays in the equation. Steady state is F=mg=drag, drag goes with V^2 so you have a sqrt(m) dependence in Vterm. On the wing the applied torque must be a sum (integral) of the aerodynamic force*distance to the roll axis and there is no Ixx term in the applied torque.

I'm surprised the roll seems to stop on-a-dime when releasing the sticks. The aerodynamic drag in the roll direction should go to zero as the rotation rate slows. You would think it would slowly coast to a stop.

Carl