Stupid question, but I find the compartment extremely practical; my current Dakine is slowly giving up the ghost. When I have mine on my back, it has a small fleece pocket on the left (I can open the pocket and reach in while carrying it) where I put my keys. On this model they show a passport. Does it have to be something flat or would a key in the compartment press into the back? It also seems to be higher up, so I'm afraid the keys will fall down quickly. Does anyone also use it as a key compartment?