If you are worried about your gear, then you shouldnt leave it there.
I am worried about it, but 100% safety would mean having my gear at home and not gigging it, wich IMHO defies it's pourpuse... I'm just trying to find a balance I'm confortable with.
That's why I wanted to:
A) find a way to tell if it is in fact being used
B) If it is, block it's use without moving gear around.
By the way, I'm based in Madrid (Spain) and English is not my mother tongue... sorry for any mistakes, Should it be called metro?