Well apparently they are quite heavy and also low on power...
They were recently hyped up and everyone within 1/2a just had to have one, but I'm yet to see one that has actually been in the air.

Best thing would be to bench run it and see what kind of numbers you get out of it. If you're scratch building you could aim for something like an oldschool glider, sort of assisted free-flight, rather than a wardbird style that would require a strong and lightweight engine.