Found a small bug, don't know if it's been mentioned or patched yet, but here it is.
If the value of health that you have set for the player to lose when dropping is more than the amount of health he has, the value goes negative resulting in invincible players, so if you have 1 hp and the amount is set to 2 you will become invincible when you let go.
If the player has exactly the amount of health set to be lost, he becomes 100% invincible, he cannot be hurt in any way by anything even fall damage.