have you seen the DQG 18650 II? If I had an 18650, I think I'd have a DQG to put it in.
^ X2
If you want a clicky you might want to look at the Convoy lights. You can select how hard it is driven (therefore runtimes and brightness) and the tint of the emitter. They are inexpensive and good quality.
Convoy S2 Cree XM-L U2-1B 1400ma 2-Group 3/5-Mode EDC LED Flashlight
To switch mode group: switch to low mode and wait for 5 seconds.
As soon as you notice a quick blink, half press the power switch
and mode group is then toggled.
Group 1 (5-Mode): Lo (5%) > Mid (40%) > Hi (100%) > Strobe > SOS;
Group 2 (3-Mode): Lo (5%) > Mid (40%) > Hi (100%)
From a 3400 mAh battery one might expect:
low: 30-35 lumen: 40 hours.
mid: 150-200 lumen: 6 hours.
max: 400-450 lumen: 2.5 hours
OK so I made some notes:
the S2 is 124 mm long, and it takes unprotected and protected batteries, both button top and flat top.
the S4 is 119 mm long and the site states that it takes FLAT top batteries
The S5 and S6 are 115 mm long, and the Stainless steel S7 is 116 mm long and those three only take flat top unprotected batteries.
the S3 is also 115 mm long and there is no mention of battery limitations (You might want to check with them first, but looking further...)
I found one review of the S3 that states that the "Sanyo protected batteries don't fit. Much longer."