my results on a S10-L2:
AW IMR 16340 - 3.7V – 550mAh - around 58min on high, a bit flickering then it steps down to medium.
nitecore RCR123A 3.7V 650mAh - 1hr 05min on high, then it abruptly switches off completely. no warning, no flickering, and refuses to turn back on.
next i'm going to try the AW IMR again and let it dry its juice till the light steps down to low.
looking at such battery behavior, it's safer to use AW IMR which steps down to medium so won't be caught with your pants down suddenly in the dark without warning.