The part where "threshold reached, all content visible and unlocked" is what worries me. That means, any content can be visible and unlocked to anybody, and the only barrier is some threshold where Apple pinky-swears it would never look unless it is passed. We all know how well it works with NSA wiretapping, and even if Apple right now is sincerely committed to hold their promise, they could decide otherwise - or being forced to - at any point in the future. Once there's a door and there's a key, they key will be used to open the door, and it will be used for any future purpose the key owner wants to.