First forget the engine out scenario, ain't going to happen. What will happen is you'll loose one of the three cylinders, which effectively cuts your power in half. Get a Mac Danial's on board glow driver, that way when you lose a cylinder you throttle back to light the plugs, get your power back and fly away happily. You can also set it to keep the plugs lit all the time, but that uses more battery.

I had one in a Kange WACO Bipe, it's 72" WS, it flew it well, it could climb at 45* angle, very nicely powered, and sounded so good.