Actually, steel does snap, and aluminum does bend. But that's not important. What IS important is that bending is WAY overrated as a safe failure mode. That, I am sick to death of almost more than anything. Bending isn't some benign and gentle form of failure, and it certainly does count as failing "catastrophically" under the right circumstances (which are quite rare for both steel and aluminum).

Again, experience tells me otherwise. I've done my share of time working in a couple of different bike shops, and saw enough broken bikes to have some idea of what I'm talking about.

I've seen plenty of aluminum frames with dents and bends from smacking into things. If it's dented or bent in a non-critical area, like in the middle of a tube, it's no bigger a deal than with steel. As I already said, the stuff DOES bend. And again, there's just no reasonable way to argue "if I had been riding aluminum I would have been injured much worse." Chances are good that you're wrong about that.

Now, I've never ridden an aluminum fork into anything because, like most people, I've never ridden an aluminum fork at all. They're relatively uncommon. I have no experience with how most of them fail and can't say anything about it. But I've ruined two steel forks in the course of two months before, and they broke very differently. One was a leg cracking off from fatigue, and it WAS an abrupt failure from my perspective - the fork went from no noticeable difference in performance to completely compromised pretty much instantly. Don't try and tell me that, had it not been secured by a front rack, that the fact that it was made from steel would have helped me avoid dental work. The other fork I broke because I wasn't looking where I was going and rode into the back of a convertible at an intersection. I ended up on the trunk lid. I was going slowly, 10 mph or less, but it still wrecked the fork. Yes, it bent instead of snapping. And the good that did me was my nearly eating pavement when I remounted to go the 20 feet to get out of the intersection, because I couldn't steer the bike anymore. The point is, if you hit something hard enough to bend or break your fork, you're going down regardless AND the bike will be unridable. That's not to mention pretty good odds that you've just wrecked the frame as well, by ovalizing the headtube and/or bending or cracking the top and downtubes near the headtube.

I'll repeat myself for the final time: equivalent failure types in frames built from different materials are more-or-less equally safe or dangerous. A failure of the chainstay or seattube is benign, a failure of the fork or headtube is extremely dangerous. This is true whether it snaps or bends, whether it broke from impact or fatigue. Frame materials and the various myths surrounding their failure modes aren't particularly relevant.