I have not found small wind turbines working at their maximum in very strong winds, e.g. 25 to 50 m/s. They peak at 15 m/s at the best, and stop at 25 m/s.
The Makani turbines are designed for apparent winds of around 50 m/s. But we do not know their lifespan.
So I tried to see if we could deduce anything from electric car motors. On the one hand they can run at a high rpm, then their lifespan is long (far much longer than that of a heat engine), and their power/mass ratio is high. I provide an example:
Tesla’s high-performance copper rotor motor generates 300 horsepower while weighing only 100 pounds, making it the world’s lightest electric vehicle electric motor (45.4 kg).
The motor can spin at peak speeds of up to 14,000 revolutions per minute.
Now a blog (in French) about the lifespan of an electric motor:
Durée de vie des voitures électriques - IZI by EDF indicates several million kilometers. 3 million km at 80 km/h (arbitrary numerical data for lack of a more precise example) would give a little over 4 years continuously.
This may be an acceptable lifespan for a flygen, although significantly less than that of a conventional wind turbine.