I have done it in more elegant ways and it certainly is practical. I have certain reservations about doing it this way but even then it will probably be fine. It is rather cruel to the alternator and the blades but for smaller machines it may not be as bad as I would have originally expected. If the switching rate stays fairly high then it may be no worse than a single phase alternator with its inherent vibration and torque pulsation.

AirX gets away with something that has similar mechanical effects and I believe SWWP are trying it on bigger machines.

Anything strong enough to survive in a gale of wind probably is capable of taking this sort of loading in its stride, but if you ever witness a direct short on a 3 phase 1kW pma driven by a motor on a bench test you may share my initial fears. In this case it is not a direct short and nothing like as bad.

Just keep an eye on stator mounting bolts etc for a while or use plenty of loctite.