Spoke with him today and he was pretty open with me on what he did, and expressed a willingness to test some improvements I have in mind.
Existing coins are safe, of course: one had to have physical access to your coin to compromise it, and as I understood it, there was slight visible damage in the process. Remember, this guy attacks stuff like this as a hobby, it is not as though everyone out there will suddenly succeed in attacking their coins.
The rimming I do on the 1 BTC silver may be more challenging and he says he will be getting one tomorrow to attack. With what I know of the attack, making laser marks on the hologram will make it far more difficult.