Haikelite SC04

Anyone ever tried haikelite SC04? It appears it can work in several configurations:
1 - 26650 batteries or 2 - 26650 batteries (with a supplied extension tube) or 2 –26350 batteries
Gives off 2500 lumens on one battery and 5000 lumens on 2.
Has a decent 600 m thrown.
Might be a good light for me even without a thermal stepdown for a while due to decent head size.

Sound like 2 –18350 configuration is optimal giving off 5,000 lumens and not very large. the beam profile seems good from the reviews and the throw is claimed at 600 m. My fear is that as the voltage drops it will go to the next discreet level which is 1500lumens?? Not bright enough. Anyone has experience how long it maintains 5000 lumens on 2-18350 bateries connected in series? and at what voltage it goes down to a lower level 1500 lms ( basically becomes useless)
thanks