That picture they show is nothing but a spiced up version of a classic miller turbine which used 2 sheets of old iron and some scrap steel and it was used for years over here in Oz for water pumping.

Well if the scrap yard has some cheap plate just maybe this bug might produce yet another time wasting project.

I don't know how much noise they make. It might get annoying listening to swish/swish/swish all day long at work or at home (if you lived next door to one).

Seems to me the savonius is taking up far too much of the swept area and interrupting the airflow between the darrieus blades during the highest-power part of their rotation.

I've seen a similar design where, instead of being proportioned like a pair of big juice cans the height of the darrieus, the savonius starter-rotors were proportioned like tunafish cans, one at the top, one at the bottom, leaving all of the "eggbeater" except the narrow part near the ends of the blades (which does about squat) open to the wind.  THAT should have essentially the Darrieus' efficiency with the Savonius' stall torque to make it self-starting.

Also the savonius rotors in this one seem exceptionally wide.  They have a max power TSR of about .8 while the darrieus is in the 6-7 range.  So the darrieus rotor should be almost ten times the diameter of the savonius, or maybe 6-7 if the darrieus is supposed to spin up the Savonius until it just spins at a rate that makes it transparent to the wind.  Looks to me like a bad mismatch.

(Then again maybe I haven't computed it right and the "transparent RPM" is much higher.  Or the Savonius sucking out power in the middle helps to even out the vibration of the Darrieus' torque vs. angle.)