So I just watched a story about how the movie Toy Story 2 was almost lost due to user error. Check it out here. Moral of the story: backing up isn't enough. You gotta test 'em, yo. They got lucky and didn't lose 30 man-years of work. The old adage goes "better lucky than good". If you have a choice, be both. Most of us don't, so choose to be good.