I've recently visited AW's IMR page ("Part 11") and there's no IMR 14500 in post #1. Has it officially been released yet? Fixing for an order soon, I'd add it.
I was measuring a 3*AAA battery holder from a giveaway 9-LED flashlight. I measured it as a would-be 20500 in terms of lithium ion specifications (20mm wide, 50mm long). TMK, there is no such thing as a 20500 in ANY (available) lithium configuration, though I've seen people request the same. But I think the slew of 3*AAA flashlights will drive the market for them. The closest thing is an 18500, which AW actually makes an IMR for. Sometimes you can also squeeze an 18650 in those lights, usually requiring some modification
So apparently "wider is better" when it comes to lithium batteries, eh. Makes sense, as a "C"-sized li-ion has way more capacity than an 18500 or even an 18650. Ultrafire is now selling an 18340, which I applaud.
I personally think the good ol' "C" cell dimension is going to be an up-and-comer for the flashlight enthusiast (bright light) community. Standard size seems to be 25500 but AW's IMR is 26500. A single "C" body flashlight could really come across looking like a small if thick flashlight and have awesome current & capacity. The cells are already available, too; no whining to manufacturer. More mfr's just need to start making lights for them. In fact, aside from Nailbender's partner who makes some kind of DIY host body for C cells, I don't know of ANYONE making a 1*C li-ion powered flashlight. Reading the Nailbender threads really convinced me that C shall be the way to go in the future for high current. At that point (at least direct-driving) it's not so much about nominal voltage but everything else: current, heat, C[apacity], internal resistance, Vf [voltage forward in LED].
I wish I could get a C cell into some of those cheapie 3*AAA's! Would be GREAT for some awesome mods!!! Just put a C up to a 3*AAA host again... it's SO close... but alas.... Actually, if you found one with an unusually wide tube, I could see it fitting, at least a real Alkaline C I just measured is 24mm across not 25. I know there are brick&mortar stores who've sold C-alkaline LED's (or regular incans) loved by modders but all are 2+ C batts. It's like a twice-as-wide 14500!