I have one, usually run it on 2X 26650's or 21700's in adapters. Seems like my 6D ML300 rated at 694 lumens is good bit brighter than my 746 lumen rated 3D ML300LX and almost as bright as my nominal 1002 lumen 4D ML300L (also running on 2X 26650's or 21700's in adapters). I think the shorter 3 and 4D versions handle better than the 6D which is not as well balanced and feels a little awkward and needlessly long.
But if long and heavy is what you are looking for you can run it on full capacity NiMH's and add a barrel extender to approximate the size of the old 7D Mags.
