I have one in one of my Raptors.

It had a reputation as being a bit of a clunker but mine has run like a sewing machine for the last 4 years with only one piston and liner in that time. A bit underpowered nowadays but has pretty good fuel economy.

However, the aero with different head and longer crankshaft version has a fantastic reputation as a very reliable engine. I think some people ran the heli version with the heat sink head in cowled scale planes where cooling can be an issue.

I think you are more likely to sell it to a planker than a heli flyer.