Some of you guys are missing the point of an optical kill switch. The really great thing with the switch is that the receiver has to be on and powered up before the engine ingnition will even be activated. Meaning, you can's start your engine unless the receiver has power. And, if for some reason, your receiver looses power in flight, the engine shuts down. You can have all the manual "hardware" installed i.e. choke servos, throttle servo kill positioning etc. but if you loose power to the receiver on one of these systems, you'd better hope your last opertating position of the throttle servo wasn't on full throttle.

Another good feature is not having to adjust your throttle trim every time you start an airplane. Many people use throttle trim as their "kill" mechanism. With an optical kill, just flip the switch. Now, the next time you go to start, your not fumbling around trying to find the "acceptable idle" position. It's where it was when you last flew.

I've been using Robert Richie's Smart-Fly for a couple of years now. I won't have a gas motor without one.