For me it is all about knowing what I'm dealing with and take the adequate precautions, mitigating the risks to an acceptable level.

Unless you plan to ask permission from your neighbors, there is a certain ethical element to storing fuel in an apartment complex. On a practical perspective, I can think of at least one way of handling the risk of leaking canisters inside an apartment (think plastic crate with propane detector at the bottom). But in case of a fire I would not want fire fighters to search my apartment: The canisters WILL go KA-BOOM when the fire reaches them. The blast should not be big enough to cause major structural damage (unless you try to confine it inside a small box), but no way I'm putting fire fighters in risk of being inside the blast zone while searching my apartment. Fire fighters will search anywhere humanly possible until proven empty. Sorry, apartment dwellers, I see no way around this.