Best gyro I've seen (and flown) so far was a Magni Gyro.
Only Problem there is the engine (2stroke, 100hp).
Here in Germany is a new set of regulations set up for gyros.
First step are Microlight-Gyros (Ultraleicht - Tragschrauber).
They made inensive testing at Trier-Föhren.
First thing they replaced there was the engine by a Rotax 914.
That is IMHO not the optimum, but a lot better than any twostroke with all its thermal problems.
With kind regards,
Robert