I'm in the same boat with the other replies you've already gotten, I think a kill switch is a no-brainer.

I also like the three method approach, throttle cut switch on my tx activates the kill switch and closes the throttle below idle, and I have a servo on the choke.

I use the ElectroDynamics units so far, but I think that my next project will have the Smart-Fly since it can be built into a board that will handle other functions, i.e. regulators, power expander, etc.