I use Almax. All chain's are fallible, it comes down time, determination and how much noise the tea leaf is comfortable making. A portable angle grinder will make mincemeat of any chain, but it'll make huge amount of noise doing it. A friend uses one of these in his garage, it proved effective with one scrote that dared to enter his man cave: http://www.henrykrank.com/index.php?main_page=product_info&products_id=2964
Almax 19 for me combined with the anti pinch pin, anchored to a Ymax Anchor. as previously stated nothing is 100% secure but they will have to make quite a racket to get the bike away. http://www.yanchor.com/Y-max 901.html
