Does Cape allow independent control of the individual rotors? If so, I wonder how well the safety system would handle a drone being flown to its maximum altitude and then having the rotors on one side run in one direction and the other half of the rotors run the other way. In my mind this would cause the drone to rotate around a vector in the horizontal plane while gravity would be pulling the drone downwards. Higher altitude would give more time to build up the angular velocity of this rotation. If then the angular velocity is high as the drone approaches the ground, the system might not have time to recover stable flight. Thus the drone might crash.

Yep good point! We currently do not allow our users to actuate individual rotors to this degree of control. Instead, we allow lateral translation to move forward & backward, strafe left & right, ascend & descend, yaw the drone, and pitch the gimbal. Basically, standard WASD + mouse game controls.

Most quadcopters don't allow for the motors to be reversed - it's very rare for the motor controllers to support this unless the quadcopter is specifically designed for inverted / "3D" flight with custom motor controller firmware and bidirectional / 3D props.

"What motor inputs would cause the hardest recovery situation" is a pretty fun question, though - I think the best you could do would be to throttle the two motors rotating in a given direction to zero (both CW or both CCW), which would induce instability in multiple axes at once. But there's probably something more creative I'm not thinking about!

The obvious next question: where do I buy such an uncrashable drone for my own personal use? Is there something like that readily available on the market, or is that the company's secret sauce?