From what i have seen, most home invasions are smash and grabs. They dont want to spend a lot of time inside a house. They want quick, easy, and simple to sell. So, no, this wont stop someone specifically entering your home to rob the safe from doing so, it would keep the vast majority of smash and grabbers away as they wont take the time to bang on a safe or pry it open.
If it were me, id keep my "workin' guns in it, stuff I need easy access to, but want it out of the hands of most people. But I'd store my "heirlooms" in a different place.