Well, you wouldn’t immediately gain a lot, but I suspect that 21700 format development is still fairly heavy, while 18650 is about as good as it will ever get now. So, since you would be gaining a little bit now, but also ready for future 21700 improvements, it might be worth going for it, even with just 2S3P.
Actually I just realized that 2s3p is not possible, we need 4S input which we can’t do with 6 cells. I thought that had come up before but forgot why it was dismissed.
Well, as we probably talked about it before, using a 2S setup instead of a 4S would require much higher current.
Because of this, the current paths would have to be even thicker, and the overall efficiency would go down by a bit.
Also, using a 4S setup instead of a 2S setup allow the easy use of the GT70 parts instead of requiring new hardware and more development costs.
Yep, that^.
Wow that’s a beast! Any info on the driver? Buck or DD/FET?
Well, maybe. But the Boost HX is a ~3v chip, so I don’t think the slightly higher current going to the buck driver will be enough to cause problems. Obviously, I could be wrong. 
Also changing from 18650 to 21700 already requires “new hardware and more development costs” so the difference 2S or 4S isn’t significant in that regard.
It’s not going to use a buck driver though.
A 250W-300W flashlight sized buck driver would be extremely expensive, where a FET+linear regulator design would still work adequately with 4X XHP70.2s.
And besides, the 1mm2 Olson HX Boost only comes in 6000k+ variants, which look way too blue.
Lumintop could easily offer a CW XHP 70.2, and a NW 4000k XHP70.2 model, which would easily satisfy almost all customers.
It will be using a beefed up version of the GT70 driver basically, so 2 channel FET driver.
A buck driver would be nice but a ~40A buck driver is no simple task and it would be very large, I know this from experience on a light that never went public.
The boost HX is an interesting idea for a future version of the light but it will not be something done at first that is for sure seeing as they are not even out yet.
Can it run on 8 AA?
lol, not exactly.
Ohhhh shoot…lol…cant wait for it….
Is the head the same size as the BLF GT? Is the heat sink the whole head? Looks to be one piece, any info on that? Any side pictures to see how deep are all the fins?
Yes, same basic size as the GT / GT70.
Yes, all those fins on the head are used for heat sinking pretty much.
Here is one of the earlier CAD designs, I can’t find the latest one at the moment but it as only minor changes.
The cooling on this light should be quite good to say the least.
Thanks TA! 
No idea, looks great though! Just saw it on FB this evening. Hopefully should out-do the old Shockers - think the best I got was over 500 kcd. Some slice&dice action on those biggies should do.
4 xhp70.2s in huge reflectors vs 9 xhp35 HIs in smaller reflector wells would be an interesting comparison. seems like the gt4 will make for slightly more lumen but slightly less throw.
Well, for one, it will have better QC, replaceable cells, non exaggerated specs, NarsilM.
And where did you find an R90C for 200$US?
The lowest price I’ve found with a coupon is 280$US.
It will be more reliable than the R90C specially at the driver, step down is user-controlled, probably brighter, much better heatsinking, and most likely without the fogging issues of immalent lights.
Sadly max output will drop accordingly to the battery level, being a direct drive setup.
And can be used with 8 18650s for much better runtime.
And you can get the light in Neutral White rather than Cool White.