Thanks that's a good start.
My own thoughts (being a helicopter person) are that Gyroplanes/Gyrocopters/Autogiros could do anything that a helicopter could do that did not involve actual hovering. It is possible, I suppose, That the big helicopter manufacturers got together with the politicians to stifle any real development of the gyro as a realistic work platform once the helicopter had been invented and developed beyond a certain point. Hence we're stuck with a very 'expensive to operate' machine with no realistic alternative. More comments welcome.