The Hirth F-36 does have one definite boast ! According to this it has a 1000 Hr TBO at 75% power.
http://www.aati.com.au/hirth/f-36_engine.htm
One thing that bothers me about the F-36 is this. If you search the web you will not find much on this engine. You would think that a whole host of Paramotor manufacturers and other craft would be utilizing these engines. This does not appear to be the case. Is this engine one that could suddenly be pulled from production ?? Makes you wonder.