Yes, it is particuarly tough on the cells, and most likely any higher power output will yield diminishing gains. But it could be a fun project to try to improve the driver even if it is an impractical endeavour. For example, a multiphase GaN converter would be fun. As for the LEDs, Manker calls it a 'searchlight', though I would definitely not consider the MK38 as a thrower; it's more similar to say the general-purpose SC700d, just a lot brighter.
I'm interested in the USB Charging section as well, and how the 'battery pack' is assembled. Having removable batteries in the 21700-only version seems like a tricky option since the flashlight will be drawing >100W per cell at peak draw, making interconnects and such potentially difficult to implement reliabily.
icpart is correct. At the moment, the Acebeam X50 comes in a high CRI variant. I asked Acebeam directly and they told me that it will be using GT-FC40 LEDs. They're not very efficient, but they do produce a really nice tint as I found in my Lume-X1 KR1 build. On the other hand, the Manker MK38 comes in a throwier variant using Luminous SFT40 LEDs, which supposedly halves the luminous output but doubles the intensity.
Photography Fill Light|AceBeam® Official Store | Flashlights, Tactical Lights
Mankerlight MK38 Satellite (Power by 3x 21700 Batteries) - Mankerlight Official