I find the ultralight thing a bit confusing. Dropping lots of the pointless baggage and going light is fine - but the difference between carrying an 8lb pack and a 9lb one seems pretty moot, and there seems to be some sort of martyrdom about going as light as possible. You do expose yourself to some extra risk if there is a problem, but there is ALWAYS a payoff between completeness and convenience (unless you keep your BOB strapped to your back 24/7, and even then, what about an extra few litres of water or MREs? :-))

That said, some of the novel solutions these guys come up with can be pretty interesting.