I've been using TSA locks since they first became available, and remember a few occasions where my suitcase was searched, then re-locked with the nice "TSA was here" note inside. More recently, it seems to me that my suitcase has been rummaged through without any note being left, but I haven't actually lost any locks yet. The only advice I would have is not to check anything you absolutely can't afford to lose, but you already have that covered.