Lieren, Thanks for the help with the link.

I personally have used a New York F. U. and an On Guard Brute (5000 series) on the gritty streets of Downtown L.A. for many years with no problems (both use the disc/wafer tumbler system).
I can agree with a previous poster in that it is Extremely Important to make sure the keys are completely inserted into the lock. (if key only makes a quarter turn in lock then Stops. Instead of the half turn+, Then the key is not completely inserted, Trying to force the key to turn will break the key inside the lock).

I notice that both O.G. and Big K have made the plastic key handles smaller since I bought my locks (to reduce leverage/ease of breaking off key in lock?).
Also users that mount the locks solidly on the bike either using the craptastic frame mounts or a rear rack have problems with road vibration causing the internal disc/wafer tumblers to wander out of the home position alignment, making complete key insertion difficult at best.
Also important is ongoing and regular lubrication and maintenance of the lock internals AND the U shackle (hardened steels used in U lock shackles are much more vulnerable to corrosion as an artifact of the hardening process).

In the last few months I have been attempting to lighten the amount of BALLAST I'm rolling with on the Sporty Quick bike. A combination of Pinhead Skewers, Seatpost, Headset, and Seatlocks plus an ABUS mini U lock, O.G. 7 inch mini U and two 10 mm cables. So far so good.