Have to ensure no-one opens all the doors at once. Could turn it into a single-pylon tilt-rotor.
I particularly like the multi student arrangement. Slash the cost of instruction. You'd have to have the instructor sitting at the back, with a long stick to clonk whoever's doing it wrong this time on the head. And all the other students would have to sit there with their hands in the air. A Robbie full of surrendering students, great!