So they want to make a soda can light.
I would suggest using a different battery tube than the default SRK battery tube, just to distinguish themselves from the many many cheap crappy clones with the same battery tube design.
7 emitters would fill the head nicely, like a flower pattern (6 in a circle with 1 in the middle)
I guess FET DD drivers sell because of the wow factor on a freshly charged cell, but i would like to see a current regulated driver.
With 1S4P battery config you can supply 7x 3535 LEDs with the necessary current.
Not overdriving them will give better efficiency too and it will stay in regulation until the battery runs low, especially with low Vf LEDs.
High CRI Nichia would be nice i.m.o.
The right TIR optics would eliminate tint shift when you want to use LEDs like XP-G3, and it’s probably cheaper than an aluminum reflector plus glass lens.
They could use a 7 in 1 TIR, like the DQG 3rd 26650.
I guess though, that traditional reflector + lens will sell better, because people expect an aluminum reflector.
With many 3535 LEDs (with appr. 2mm² Light Emitting Surface, like 219C and XP-G3) you can use smaller optics for the same throw, which also means they can be shorter and with 7 LEDs
With a (regulated) FET driver in stead of a buck or boost driver, the driver board can be flat.
So in all, they could make it a short, compact light.
…but maybe they just want to make a good SRK clone…
Maybe they should use 3x or 4x Luxeon V and drive them hard and get close to 6000 or 8000 Lumen.
Yeah i would like to review it if they want me to.