From the review and links it seems like a good solution for regular use as well as for emergencies. And if I get an Arc 4 flashlight, I'll be able to share the batteries between them in a pinch.

Quick question: I'm taking up backpacking, and the review seem pretty glowing. Would it make sense to also carry a first-stage filter to reduce cloudiness? Normally, I know Doug finds them unacceptable because alone they don't do anything about biologicals-- but in this case that's already covered..