let say i put a lvl 3 spirit in front of my door to guard it and give me a headsup if anyone opens the door or is otherwise intruding.
does any possibility exist that anyone is bypassing him without me noticing? if he get killed, i feel it. he is dual so he sees invisible enemys and looks trough camo, he only looks at one door, so sneaking should be impossible (at least open the door).
I'm gonna reiterate the wisdom of the advice that lots of things that could work against a metahuman doing the same job could also work against a spirit.
Concealment/Stealth (spirits are exactly as fallible at being sneaked by as a metahuman)
Fast Talking/Conning ("Hey I'm authorized! No need to report my presence as an intrusion/
of course your master "meant" for allowing ME through.."/Hey go back to master to doublecheck that he really did mean for you to keep ME out)
Being backdoor'd (Going into the room by way other than the guarded door. You can almost always CUT your way thru a wall to force another way in, if it comes to that. If there really is literally only the one way possible to get into the room, then you hardly need the expense of a spirit to make it hell to infiltrate)
Being evacuated (Granted, there are more environmental options to force a metahuman guard to vacate the guard station, but there are still ways for an inventive and well equipped shadowrunner to force a spirit to abandon its post)
That all being said, I have a problem with the premise in the OP. That being a spirit makes a mandatory chokepoint pure hell to get through:
When it comes to Runners being forced to go thru a chokepoint and it being impossible to bypass said chokepoint, then it doesn't matter what kind of security is on the chokepoint. Computerized sensors, Metahuman guards, or drones would all be equally effective as a spirit.