I'm not too concerned about this particular method of defeating locks. Works great on a lab bench, but not so easy on a typical bike locked to a rack frequently with other bikes right next to it. In that case getting the lock cold enough isn't as easy and it wouldn't be trivial to deliver the hard hammer blows cleanly without risking serious damage to the bike (and a smashed bike isn't worth much to the thief). Portable power tools such as angle grinders pose a much greater threat but are noisy and conspicuous in use.
I wouldn't put much faith into collecting based on the Kryptonite guarantee. AIRC there are quite a few documentation items required in order to collect and even if you have kept all of those you also need to return the broken lock. Hard to do if the thief decided not to leave evidence like that lying around.
Last edited by prathmann; 11-23-12 at 04:03 PM.