There is an additional variable that, of course, would be less practical to test, and one that is very important to me personally: shelf life, where the lithiums would really shine. I have, among other things, an assortment of flashlights that need to sit for, oh, a decade or so, and then perhaps be used under difficult conditions. If somebody could prove to me that Energizer Ultimate Lithiums really have a usable shelf-life of fifteen years as-claimed, THAT would be massively cool.
Inevitably, your survey is a bit UK-centric. I suppose it has to be somewhere-centric, at least for starters. Perhaps a mail-in battery donation campaign from around the world? For instance, it would be nice to get some US market value brands (Ray-O-Vac, Enercell by Radio Shack, Sunbeam from Dollar General, etc) into the game.
A very good effort at a very difficult thing, though. This has to be the most comprehensive test of its kind to-date. Great web site as well.