Just curious if anyone here can suggest a decent LED flashlight that runs on one CR123A cell and has a rotary twist switch? Preferably aluminum and water resistant would be a huge plus. Normally I prefer clicky tailswitches but I want something that won't turn on in a pocket accidentally.

Short of that, a similar light that runs on AA cells would be tolerable. Really looking for something in the 120+ lumen range, so while, say, a Fenix E01 is a great mini-light I'm thinking something a bit more powerful.

Here's the one I have:

https://www.foursevens.com/products/ML-X-AE

I've got an embarassingly large number of foursevens flashlights, from a Maelstrom X7 mounted to my shotgun all the way down to the ML-X. None have ever disappointed.

That's a good looking light! A little more expensive than I was thinking of for this particular application but I might have to pick one up anyways.

I know you said twist switch, but I carry a Streamlight ProTac 1L, which is a clicky, but unscrew the switch to disable it until needed... the tail switch is recessed a bit ... less lumens but a little cheaper than the foursevens

The Nitecore SENS CR may fit the bill.

http://www.nitecore.com/productDetail.aspx?id=39

This is the one that I use, great flashlight and a good price. It has a screwed on pocket clip, which I also like. Multiple light levels and twist switching. It even comes with an allen wrench to remove the belt clip, if desired.

http://olightusa.com/OLIGHT-i1-LED-Flashlight

A review:
http://flashlight-forums.com/index.php?topic=9240.0

http://www.youtube.com/watch?v=HqGyOFEGYRQ

Some great looking light! Thanks, everyone. By chance, can anyone recommend something in this general size range that just has one power setting? In other words, twist on and twist off? Seems like they all have a bunch of modes that I don't need.

I have an older Fenix that is one level only and takes a single CR-123 battery, but they do not make them any more. I am pretty sure that no one makes a single level CR-123 light, since the multi-level lights are all the rage in the flashlight world.

The Olight i1 is very simple operations for a 3 level light, I am really content with mine and the lower levels are handy when you want to prolong battery life.

There are some single-mode 1xCR123A twisty flashlights out there. I can't find any, though, that are being made with the current generation of LED emitters or by what I consider to be good manufacturers.

I don't have one yet, but I am seriously looking at a NightCore SENS. I've got 4Sevens and Olights currently, but no Nightcores.

What I like about that SENS, at least by reading the sales blurb, is that you can turn it on initially in any mode - lo, med, or hi. This solves the problem I sometimes have of wanting to have "last brightness level" memory mode sometimes, and other times no memory mode. Depending on how you aim the SENS when you turn it on determines it's brightness level. Intriguing. It also has a continuously variable mode which I personally see no need for.

The problem I have with twisty lights is that they are hard on the batteries (they smash them). It's OK if you use primary disposable cells, but I don't want my more expensive rechargeables to be damaged.

The SENS does not have a long throw however. Bright, but only for your immediate area, not long range. Looking at the review here: http://www.candlepowerforums.com/vb/showthread.php?340906 I think my choice for a SENS would be a AA version fed with NiMH Eneloops, even though I was initially looking at the CR123. The runtime charts appear that runtine with rechargeable LiIon are not that good (on high/med mode). The NiMH outputs are certainly lower, but I like the runtimes shown in the charts. Plus, I have some 180 lumen lights that I rarely use on high, so the max of 120 lumens for the SENS on NiMH would see fine for my uses. The SENS reportedly hits 307 lumens with LiIon. That is bright. But the runtimes are short at that level, and reviews I've read say it heats up quickly to uncomfortable levels (for holding in your hand) at max output.

Another interesting light is the Olight S10. But that one has a push botton which you don't want. But I really like the way they did the user interface on that one. Normal button pushes cycle between lo-med-hi. Press-and-hold gively you ultra low moonlight brightness and double-tap give you strobe. I like the way they "hid" the moonlight and strobe modes. You can get to them easily, but they don't get in the way during normal cycling between lo-med-hi.