dougmc

OK, but the DealExtreme lights don't really let you pick your beam width. In general, most of their 18650 lights have the same reflector and similar emitters and therefore the same beam, and I'm not sure you can change the reflector very effectively. At $35 or so each, it's really not that big of a deal, if you don't like what you got you can give them away and spend a few hundred on what you really want.

That said, I think this one is the one to get -- it's got the newer emitter and is therefore a bit more efficient than the older models. As for modes, skip the two mode one (it uses a resistor to dim the light - inefficient) and all the 5+ mode ones have low, medium, high and flash, plus some useless stuff like SOS.

I have been tempted to make a small black cone for my sku 16501 light to reduce the beam width a bit so I can aim it a bit higher without blinding people, but it's not that big of a deal.

As for runtime, buy two lights and four batteries and keep a battery in your pack, just in case. In medium mode, they last about 4 hours, and in low mode about 8. I leave mine in medium mode most of the time. When the battery gets weak, the light gets slowly dimmer -- you're likely to not even notice it until it gets bad, but when it does, you'll want to replace the battery.