I have never been comfortable leaving equipment over friends homes...mabey because in a fit of rage my friends brother put a guitar through the front of my 2x12(a loser to this day).After thinking about my options to be reimbersed it turned out I could do nothing since I left it there and he wasn't responsible/his property crap .I couldn't really pound him either since it was my friends brother(gee sorry dude,didn't mean to brutalize your family member)

Another good idea is to write you social security number some where discreetly on your gear(besides your guitars,i'd always take them home)like on the underside of a cabinet(use a sticky label).