AXL72:I would be too paranoid that someone from the other group would lock the gate behind me and my group in retaliation or as a sick joke.
How about just locking the gate behind you, or are the gates plated, only able to be unlocked from one side?
Things may have changed but when I was there the lock that was used couldn't be locked without the key and we kept the key with us. the few times that there were other teams in the cave, we talk ahead of time and the team that's the furthest in always has the key...an exiting team will hand the key off to an entering team. There is only one line so two teams aren't going to pass eachother without knowing. you don't want the gate locked while you're inside...what if you lose the key?
During the week when there weren't many divers around, we just left the gate unlocked and the key was stashed in our room so no one could lock it.
The biggest problem we had was OW divers messing with our decompression tanks. I would caution anyone who dives the cave to give this some thought and take measures to prevent tampering.