Dave, I've actually seen the Dornier Do-31 at the Munich Deutsches Museum
http://www.deutsches-museum.de/en/fl...vtol-aircraft/
The problem with all of these is high disk loading and complexity. High disk loading is bad because it reduces all up weight for a given power, complexity is bad because it reduces the percentage of the all up weight that is payload. There is also the cost of all those turbines, props, driveshafts, gearboxes etc. I notice you have not sketched in any structure for the rotors.
Separating lift and thrust is good, if only because it allows a streamlined cruise attitude, but for good hover capability you need as large an uninterrupted rotor area as possible. This needs to be as compact a configuration as possible or you limit where the machine can demonstrate its flexibility.
Later thought:
Hadn't we all agreed that, despite the assumption of incompressibility, having a puller prop ahead and below a rotor
did in practice produce a measurable increase in pressure hence reduction in pitch?
Alternately put a pusher prop above and behind a rotor. Besides the rear rotor is best off being out of the streamtube of the front rotor. Like Chinook this reduces BVI vibration and increases the intake area. So you want that design to fly backwards. Still monstrously inefficient though...