The single point of failure I refer to is the bearing which attaches the rotor to the aircraft. Without the regular professional inspection which a proper helicopter gets, its just not going to be very safe.
Autorotation is not a fallback mechanism for an autogyro. Its the only way of staying airborne. If the aircraft changes attitude suddenly, the rotors will lose angular momentum due to precession. If the aircraft goes into negative g, the pressure differential across the rotor disk will reverse and the rotors will lose angular momentum that way too.
