This requires your heart to actually beat so the pros and cons on both sides are different: A thief can't steal your heart. A thief could still threaten your

This requires your heart to actually beat so the pros and cons on both sides are different: A thief can't steal your heart. A thief could still threaten your life. You can't repudiate your heart. If you get a heart transplant, at first the 'system' might not have a workflow for changing your expected heart signature.