Was writing something on Jayki about multiple AA lights with two or 3 NiMH. Then remembered a review of the Aurora SH0030 multimode I wrote there. Our esteemed host says runtime is important to him - I think I have the ultimate. The light output is less than a Fenix E01 though. With an extension from an Ultrafire C3 and two cells it gives 27 lux (Lightbox) on High (Drawing 12.2mA) - a Fenix E01 gives 37 in the same lightbox.
9 lux on medium from 5.11mA
On high in this configuration it should give a couple of hours under a week of light with a pair of Eneloops. On medium you get more than a fortnight - overr 400 hours with the measured capacities of my Eneloops.
The numbers from my light tests are always to be found here.