I'm very comfortable with the Emcotec SPS which provides for a complete electrical disconnection of the batteries. Beyond that I go to extreme lengths to ensure safety. I cannot get RF unless the radio is in the start up "Motor Off" condition with a flat -150% throttle curve. In addition the RF will not turn on unless I have the throttle stick at full low. Once on I need to turn on the receiver, but even then there is no power to the ESC. I have to remove the magnetic arming plug, flip one switch to turn on the throttle/motor curve (I call this my "Master Switch") and then finally move a slider to the center postion which turns off the throttle kill and turns on the timer. NOW I can finally put power to the motor.

So that is:

1)TX on with throttle at 0 and "Motor off" condition set. Both required before RF transmitted.
2)RX on (ESC will not and cannot arm without RX signal)
3)Arming plug pulled
4)Master Switch moved to "Motor on" condition
5)Slider moved to turn off throttle kill and turn on timer.

My failsafe it set to zero throttle and my ESC will turn off power to the motor if it loses signal from the RX.

So:
Move slider from center = motor dies (regardless of Master Switch position)
Move master switch to off = motor dies (regardless of slider position)
Failsafe (RF failure) = motor dies
RX off (RX battery dies/RX fails) = Motor dies
SPS fails with anything other than a hard short while ESC armed = motor dies
SPS fails with anything other than a hard short while already off = ESC will not arm.
Hard short has not been reported with the SPS and I'm betting if one happened it would cook a FET or something else to break the circuit.

Upon landing I immediately turn the Master Switch to OFF and move the slider to full OFF. Helper puts arming plug back in which disconnects battery power.

All of this is a piece of cake with my Futaba 18MZ radio.