I don't know why you guys need to shut the engine off with the choke. I think a muck elegant idea is to cut the spark off. Look at the chain saws and weed eaters. That is the method they use. But what do I know? I am just a beginner in gas airplanes.
Here are my reasons for using what I use:
The two ways to kill an engine's spark with the TX: Servo actuated switch and FO Kill switch. Third option to kill motor, choke.
1) Servo operated kill switch
--- adds a second switch in series with the manual switch to fail... more likely to have problems
--- servo will most likely be up front near the switch... don't like ot have RX electronics within 12" of IGN electronics
2) FO Kill Switch - I had one of these
--- Another part to fail in series with the ignition switch
--- A second part to fail near the RX (the LED side)
--- FO cables to come loose
--- A temporary glitch can kill the motor
--- Failure most likely identified in flight when motor quits
--- If using 2 RXs in a large airplane and the RX the FO kill is on dies, the motor dies with it greatly reducing the chances of recovering the airplane.
3) Choke servo
--- Servo is back near the RX with Precision Rod runnig to the choke
--- Don't have to reach through prop when starting
--- Failure most likely identified when starting. Failure in the air most like will not kill motor... will notice at next start
--- No additional electronics in series with ignition wiring
--- If one RX dies in a 2 RX installation, you are left with either the choke or the throttle... the motor will keep running if either RX dies. In one case you are stuck with whatever thrust you had selected (better than nothing), and in the other you retain full throttle control. Of course, if the throttle RX locks out (as opposed to power failure), then you are stuck with your failsafe idle power (required in most places now).