200 bhp from a 2.0 litre two stroke is not high output, single...

200 bhp from a 2.0 litre two stroke is not high output, single cylinder 500cc motocross engines were producing 60hp thirty years ago, and things have moved on a lot since then. They probably have developed a very reliable unstressed engine.

As for the noise, give us a break, probably the least of their concerns in development, and easily sorted with mufflers, compare an unmuffled racing engine with a road bike.

Some of the noise may be due to propeller tips going supersonic, as with microlites, has not stopped people using them after all.

Very difficult to know whether this will be a success ultimately, but buying at 40c was definitely worth a punt for me.

The aeronautic industry certainly seems interested in the idea, and they probably have a better understanding of its potential than most.