Decided on a Nitecore for EDC and can't decide between these three! The D10 and Defender would allow me too stay AA, and I can choose between clicky and piston drive. I like the piston drive, but think it may turn itself on constantly in cargo pants pockets or other similar situations. The Extreme R2 is brighter, but I would have the expense and inconvenience of CR 123's, plus I worry about the venting, although this seems too happen mostly when they are run in series. If I went with 123's, I would have too stockpile Battery Station or another cheaper brand, and, God forbid, if the house burnt down, I'd NEVER hear the end of it! Maybe I've already talked myself into the AA's. Thoughts?