Dfunkman Framelocks are very convenient -- it quickly becomes second nature to flick the lock so you are much less likely to leave your bike unlocked while running in/out a convenience store.

There was a thread a couple of years ago in which IIRC there is a single instance of first hand theft. You may want to get in touch with the victim and ask how the bike was secured. But bottom line, theft is not highly prevalent (unlike on university campuses, schools or downtown Amsterdam