This is such a neat idea, but I wonder if it suffers from vibration problems. Because the blades are mounted on pivots, whenever you've commanding differential pitch, the high angle-of-attack blade will incur more drag and so lag slightly more than the low angle-of-attack blade. Thus the blades won't be exactly opposite each other anymore, creating vibration. Perhaps the blades are spinning so fast this is not a big deal? Probably would be if you scaled up though.
Vibration only becomes a problem when the scales of the drag/lag and rotational frequency are similar. My gut feeling is that this will only happen when your lift-to-drag ratio is close to 1, so not in any meaningful case.
I don't think the force on the rotor would change direction fast enough to cause a vibration. It would be more like a constant push relative to the intended tilt, or a slowly spiraling wobble.
