I read a report/test on one...it was apparently a PRC engine, looking a lot like the ASP/Magnums. The report/test wasn't kind, as I recall. One thing about engines on petrol, including spark or diesels, is that the fuel economy is so much better that the accuracy of run-time is much more variable. Both NV settings and fueling accuracy becomes a big problem. If you're flying contests, then you may need to plan for a timer or shutoff of some sort or other. And that's if you get one to run right.
I have posted before about using a small percentage of Coleman Lantern Fuel in glow fuel to improve fuel economy when the tank just didn't hold enough to get through the pattern. It works, no doubt about that. Try 4 oz per gallon or 1 oz per quart. Seems like 6 oz/gallon is max recommended, but 4 oz will make a big difference.
Steve