Some of you have mentioned insurance .. I've been meaning to get some but I don't have any at all on the cameras. I don't have a home to have homeowner's insurance for, so I can't put the gear in there
If you have renter's insurance, your stuff might be covered. Since you don't own you should look into renter's insurance. It's basically the same thing, with a much lower liability limit. When my neighbor's house burned down a few years back, my roommates and I all called our car insurance companies the next day to sign up for renter's insurance.

But, as for defending my gear... I am like Steve. Just leave the film or disk and you can have everything else. Besides, I not exactly a big person (5'4", 110 lbs), so I doubt I could "take on" anybody that tried to mug me.