Since you're going to go for the Mag85 anyway, you'd eventually be getting the 9AA-3D adapter. If you get it now, that opens up a number of possibilities.
With 8 AA NiMH and 1 dummy cell, you've got 9.6V of output - drop in a 6 cell MagnumStar bulb and you've got the brightness of a 6-cell in a 3-cell form factor. I've got a 2D host (hardware store 6 cell bulbs for now - MagnumStar on order) with the 8AA-2D adapter.
If you get a 12AA-3D adapter (more options once you go for the heavy mods, but you've gotta watch out for battery diameter), use 12 AA NiMH and replacement bulbs for the flashlight head of a 14.4V cordless tool.