Sorry, man. In the city, I double U-lock my bike (one on each wheel) and use a kryptonite cable through the seat. It's mainly a deterrent as someone who's slick could probably pull apart the U-locks.

I had my bike locked near the Main Library on 42nd at 5th as I described, and the thief took my handlebars, stem, and brifters!

As far as I am concerned a Brooks in Manhattan makes the bike a target for theft. When you decide to replace the bike, consider keeping a plastic bag on the seat to wrap over it when you leave it. Bikes with shopping bags over the seat always look like junk, so it becomes a deterrent, too.