Since the invention of the battery powered portable angle cutter nothing is safe. Those angle grinders can cut through the toughest of locks in less then 45 seconds, and the thief no longer has to worry if he has the right tool for the job. Even picking as become a trend lately and most experience pickers can get through a lock in less then 60 seconds and the whole time look like the owner having difficulty with the key. Add on top of that 99.9% of all passerby's witnessing such activity won't care the least bit.
See this as to how people react to a possible bike theft in process:
http://www.youtube.com/watch?v=J7zb8YXrmIA Even the cops don't care!
So I've always said the best defense against getting a bike stolen is to ride a used junker or a Walmart special and lock it up instead of your good bike.