For a good buck driver, Lexel was recommending 10 x 18650 to get 21 volts. It’s about the same diameter as the other options.
4 x 18650 can fit in a 44mm circle.
5 x 18650 needs a 49mm circle.
4 x 20700 needs a 49mm circle.
4 x 21700 needs a 51mm circle.
I think the one bonus feature of the MF03 that made it stand out was the added throw from the single xhp35-HI in the middle.
For the MF03 to compete, they may need to enlarge the head diameter to fit more 70.2 (from 7 to maybe 9 or 10) then maybe a bigger reflector for the xhp35-HI.
There are also TIR lenses that fit 70.2. I wonder if they would boost throw by narrowing the spill and improving efficiency. It could set this light more apart from others.
The 44mm is ideal case. Many 4x18650 flashlight has about 50mm battery tube, BLF GT is largest at 55mm.
Ya, that is the nice feature of MF03 with middle XHP35 HI. Someone has to talk to Imalent to put a XHP35 HI or XPL HI for the center LED of MS12, it may hit 250kcd but slightly lower max lumens. Or just factory dedome the center XHP 70 led, it should help. I was thinking can they dedome all the LED.