Yep, lately my job has me 15 stories underground with a 15 minute hike out in total darkness should the power go out (which it does often) and backup generator fails to kick in, so I've considered this.

If my Minimag fails with fresh batteries, it's pretty much: replace the bulb. I can do this in under a minute using light from my buddies flashlight (if he's bothered to check his batteries in the past year) or the coin-cell job on my keychain.

If a led light fails with new batteries, you'd better have a good backup as you'll be relying on it.