Just to add a couple thoughts. I have many of each, the S15R was on sale around good Friday for about $17, I bought about a dozen of them. Then the S1s were on sale for about $27, so I bought 5 or 6 of them. I prefer the feel of the s15, the length, love the metal button with battery indicator more then the rubber covered buttons, the glow ring under the lens is handy, output is just OK. The S1 on the other hand puts out 2x the lumens in a wall of light. I find the beam preferable for any close up work or searching. The clip on both of them is tighter than I would prefer, but the S1 rocks for mounting on a ball cap due to floody beam and light weight. Short answers:
1) get both
2) wait until the AA version releases with a TIR optic (I heard somewhere it's coming, but will prob end up with the rubber covered button)
3) check out angry fox E3 (14500) and E6 (16340), both appear to be made in the same factory as olight, the rattlesnake clip looks superior, and both put out +100 lumens more than the olight versions (CLAIMED). E6 has a cool belt clip mount also