What is not proven for me is that this is more cost effective than the quadcopter. The unbalanced rotors look like they will need expensive bearings. The compl

What is not proven for me is that this is more cost effective than the quadcopter. The unbalanced rotors look like they will need expensive bearings. The complex speed control looks like it is going to be very expensive by the time they have tackled the efficiency issues. This is vs using just two more identical motors. This brings economies of scale, plus you can use smaller motors. The efficiency issue alone may mean a quadcopter needs less battery capacity, allowing a lighter payload. Always interested in a novel design, but still lots to prove