Welcome Dave. If you want a serious quality, won't fail, etc., check out the L1-Red if you can find one. It takes 1 cr123 lithium, so the battery won't fail you. While it does have two setting (lo-high), and since it will run on even the lowest voltage CR123, the low can be adjusted merely by putting a weaker cell in it. My L1 red ran for 2000 hours, and I finally decided to shut-it off. I could barely read with it at that stage, but I could. That just goes to show you how long it will run on low batteries...so, you can use it with yer otherwise "dead" CR123's.
CR123's start off about 3.25 volts, so using a used one with around 2.75 or less should give you the brightness you're looking for. I'll check some voltages in mine when I get home, and see what produces a level of light I think you may be looking for.
They're hard to find, and a bit pricey...but not "pricey" for what they are. Do a search on "L1-RD" or "L1-Red" and search through some of the threads.
Also, the Gerber Recon on a low (used) AA is pretty low, although the red is not as "red" as it is with the L1. While it costs 1/4 what an L1-Red will cost you, the L1 will last 10 times longer.
Again, welcome, and hope this helps!
Dave/AOW