Thanks for the insight PilotDAR.
I agree that the de-ice on the aircraft is very much an escape aid and not a hard IFR tool. A local charter operation ran a 303 for a few years and one of their pilots chose to disregard the placard. The ice on the tail caused the autopilot to trim forward almost to the stop (unnoticed?) and in the descent to warmer air when the ice shed suddenly the aircraft pitched down quite aggressively. He recovered coming out of the clouds above a lake with the wings, fortunately, still on.
His passenger took the train home
