i am using both methods of safety.
first i used teh microswitch to turn off the jumper and have a safety line pull the pin. This line could be a electric wire you put in the tube.
This can bend all ways so it will pull all the times.
when you use a hard pin it sometimes sticks in the tube.
the one i use now is the safety pin on the backpack.
jumper is switched on all the time and the chute can only be opened when the pin is pulled.
this works best for me...
we had 2 chutes blown out when hanging under the jumpplane (ones without the safetypin in the backpack) and landing with the chute flapping behind the plane is no fun.....
it brakes like.......
but both landings were ok and no damage to the planes.