I was just talking about sailboats specifically, where the external forces are highly unpredictable and similar in magnitude (albeit hopefully a fair bit smaller!) than your control authority over the boat.

The work you did on drones sounds very cool and in that scenario (high powered motors, crazy nonlinear dynamics, relatively small external perturbation, at least from how you described it?) I don't doubt that ground truthing your simulation using mocap data made a huge difference.