The BME 50 is an Echo chainsaw engine and has a bulletproof crank, you will never wear it out...Even if you're a BIG diameter prop guy and lug it down...The carb sticks out the side instead of the back, but it's a piston port engine so there's no reed valve to leak....
On the other hand, if you can't stand the thought of an INDUSTRIAL engine on the front of your airplane get the DA....