Thanks davidfor. Unfortunately, I think I was already partway through the book when I started this battery life test... so imagine that won't help. I'm not trying to establish a definitive test or anything, just wondered what could be expected as others were having difficulty.
If I was going to go definitive(well, for my usage pattern), I'd probably hang an R/C servo with a rubber tip attached off an AVR microcontroller and let it go to town with sixty to a hundred page turns an hour or so, for a couple of hours a day with 5 minutes to go into sleep mode and see what happened. It'd require me to start it up once a day, but that wouldn't be bad. Frankly, as well as this battery test is going and how much I like reading with the Glo lighting I doubt I'd ever bother.
Rating life based on page turns alone isn't exactly kosher when the lighting is on, so I think my test is more valid, at least for my usage. Obviously, readers of differing speeds would get different results, probably mostly based on how long the lighting is active, and of course page turns.
Oh, I forgot, I'm not really worried about them coming for my Kobo Glo as it's safely ensconced in the heavily defended abandoned missile silo in an undisclosed location that I simply call home. Bet you all thought my avatar was just a bit of whimsy up 'til now!