Actually tried this in the little industrial 2AAs. With good NiMH, it's actually a very nice little light with excellent beam quality and a nice high color temperature. Alkalines die fast like that though, and I'm curious about the 1.7v voltage-compatible lithiums to maybe overdrive the bulb a little - it didn't instaflash, but I'm not sure about runtime and if it'd be worth it (L91 cells are expensive!)
... come to think of it, this would make a great cheap car light.