I don't see a reason the system to be more efficient or use considerably less material. The wind force for a give power is about the same. So they would need the same size / strength tower (if not more). It will be the same wind force and the same load on the bearing - just with faster rotation. All the turbines going one direction tend to produce quite some rotation in the air that carries away part of the energy and thus
reduce the efficiency.
With a flexible drive shaft, there will be quite some mechanical stress and possibly fatigue to the shaft. So I would have some doubt on the time it will stand that constant bending with every rotation.
To work efficiently over a range of wind speed the wings need to be adjusted - this could be kind of expensive for so many propellers.
The flying ones would need quite some extra spacing between - so the number of turbines on a given area is rather limited and less power is possible from a given area. With turbulent gusty winds it cold also turn dangerous and may not last long.
There might be a few cases between mountains if the wind has a strong preferred direction where is might work. But I don't see it generally useful, more like
.
There was a flying type of wind turbine before, that was way more fun to watch. It was based on a kind of plane on a line flying circles and producing electricity with propellers that see the higher speed of wind. AFIAK the project got quite some funding, but was canceled after a few prototypes. It kind of worked, but not good enough.