I've gone to the Tech Aero IBEC on all my gas planes. Gets rid of the ignition battery, provides voltage regulation for the ignition in addition to the kill feature. So far I have found no "down" side to going this route. They work and seem extremely reliable.

http://www.tech-aero.net/ultra-ibec

My larger single cylinder gas engines usually have servo activated chokes but not my twins or small singles. I wouldn't count on the choke or throttle to always be able to kill the engine as I've seen cases where something broke or came loose and neither worked reliably as a kill ... and the engine just kept on running.