Very much enjoying using the Thorfire TK15S for light painting photography, in fact I’ve just purchased a second. My review is here: Review with X-ray image: Thorfire TK15S (18650, XP-L2, 1050lm)
However, feedback from other light painters is that a 10Hz strobe (with 50/50 on/off time) would be much more preferable than the variable frequency strobe.