I'm curious, Asi, if you've seen the TiGr lock
http://Www.tigrlock.com and what your thoughts are on that use of titanium?
Materials, though, are only part of what makes a lock resistant to breaking. It has to be designed to withstand the actual attacks it will be facing.
Given, as someone commented on above, that the major lock manufacturers seem not to be interested in revolutionizing bike locks by employing expensive metals (e.g. Ti) and sophisticated technologies (e.g. GPS, motion sensors), I think it's fair to ask if we've reached a point of break resistance overkill?
How would we know? Well, I'd like to know what the most common attack modes are, and on which types of locks. I don't know the answers, but I'd be surprised if it were cordless angle grinders on the racks at the bus station.
If we presume, then, that just about any decent u-lock will defend well against a quiet, portable, extending handle bolt cutter, and that most thefts are targeted based on opportunity, what really becomes important when deciding which lock to buy and use?
Perhaps inadvertently, the Gizmodo piece addressed the factors that really should go into deciding on a lock by looking at issues like ease of use, carry-mount efficacy, and weight. Also, of course price. Personally, these were the prime issues that sold me on the TiGr (along with it's flexibile lockup scenarios), rather ultimate lock invincibility.
Yes, it's a gamble on my end since I don't know what the lock is likely to face, but I'm usually locking up in high traffic areas, during the day and early evening, in a pretty safe town.
Like I said, if someone takes an angle grinder to it, I'll be shocked. Then I'll go out and buy another TiGr probably! I value my user experience above attempting to do the impossible.