21700 here.
I vote for 21700. Like side switch only but not a strong preference. Probably get 1 or 2.
Why not build it such that you could have interchangeable battery tubes to fit the same head and tailcap?
That way, everyone gets their choice and if they decided to switch to a different cell, all it would take is a cheap & easy battery tube swap? Kinda like switching between 18650 and 18350 tubes… you’d just need to have some diameter transitions built in.
Edit: as others have said, probably side-switch only. Lockout can be done by twisting the tailcap if needed.
21700 :+1: :+1:
Knurling on tube: :+1: :+1:
SP32A tail cap :+1: :+1:
21700 Host version :+1: :+1: (please make two versions of host for choice, single and dual switch, or sell the switch cap separately)
.
Also please make a version with single emitter/reflector, I think many would like a quality C8 host w/side switch.
(XHP35 HI would be nice for the complete light)
I prefer the 21700 version
A 26650 version will fit 21700 cells easy, just allow a very slightly longer tube if really required. The extra tube width is actually and advantage for stable tail standing.
A 21700 version won't fit bigger cells, less flexibility.
And please, tell 'em the 26650 tube needs to fit Power Long Battery cells (∅26.8mm). ;-)
My vote goes for 26650 version with a deep driver trunk of at least ∅22mm.
Cheers ^:)
1: I think there not will be major internal changes. Personally I know it needs more work to assemble the parts but this is rock solid when it is together.
2: It is more difficult than you think. I think If you buy a host you can buy various diameter drivers from MTN electronics and from Lexel too so the diameter isn’t a big problem. I told them to stay with 17mm or make it 20mm to make more room for wires and make it easier to install.
3: It has 5,3mm thick led shelf in 18650 version. That is thicker than most of the other flashlights have. Somebody asked to make head with less material to make it lighter so this equalizes each other to stay as it is. But I collect everything and send Sofirn all the suggestions and they choose Ideas.
Because it will look funny 
And I think id is cheaper and easier to make a 26650 tube and plastic adaptor tubes for 21700, 20700, 18650. With 18350 it will be very head heavy and unbalanced and awkward 
I vote for 26650 that can take 21700. That way 2 26350's could easily be used if one wanted to mod to XHP50/70.
I like the separately sold switch tailcap and the single emitter version idea.
Thank you for every comment. I will wait some days and count everything.
The only bigger option is 26650 after 21700.
I understand you I don’t have any 21700 flashlight and battery but the feel is great with a 21700 I can tell.
The diameter will not be an issue. The Liitokala black 26650 is also 26,8mm and I already told them to make it fit if the 26650 will be chosen.
I like the separately sold switch tailcap and the single emitter version idea.
Thank you for every comment. I will wait some days and count everything.
I cant emphasize this enough. The diameter really does make a big difference. 21700 provides a lot of extra capacity for not a lot of extra width. Seeing as this is their most unique designed light using a 21700 seems fitting and aligns Sofrin well to compete with the other 21700 lights and batteries coming soon to the market.
Triple XP35’s 26650 with 18650 liner.NO rear sw.
Just a side sw with twist turn lock out bottom.
I can’t see any real NEED for larger battery’s.
You want a stronger light. get a bigger one.
This sizee will only get too hot to hold even quicker,
they do it pretty quick now on max.
With a moon. 30\50 100%. in that order thank you.
I’ll have two please. preferably in Light grey or\and clear.
I have 3 bloody C8;s now already along.
with another 3 x S2\S2+.
PLEASE stop developing them, Chuckle.
For those who don’t want a tail mounted switch, I assume you still want to be able to mechanically lock out the light by giving it half a turn, correct?
My worry is that after a little time the anodization will start to rub through and it can’t be fixed. Is this a real issue, or am I worried about nothing?
Haha. Hilarious pic, but I think that’s a bit of an exaggeration! And I wasn’t recommending a 18350 tube, that’s a terrible idea… I’m just saying that it seems like swappable tubes is a popular option for flexibility.
It is a real issue, some lights have prevented it by screwing the battery tube against the tail PCB ground ring, that is insulated from the shell (Emisar D4).
Since e-switch gives you an additional lockout (meaning you maybe only use the mechanical when you can’t see or feel it) and considering it’s an issue you almost never hear of actually being a problem (not possibility, actually having the problem). I think it’s worrying about nothing. It’s a cheap host you could buy a new one just for the tube and tail alone should it ever happen.
M4D M4X deals has a Q8 code .Not under $45 but close.
I’m with djozz and a few others. It is heavy. The 26650 wound be too fat in the handle for my gun use too. I don’t know how tricky the manufacturing is with certain changes, but I’m sure they’ll look into just what makes sense and what doesn’t and try to come of with something that fits the market.
So IF they redesign it from a C8 to something different, then it’s a different light. That’s fine, but I’d be out at that point as I have SIX current hosts and I’d probably just keep modding them 
But, if Sofirn made JUST tweaks for a host (and maybe a RevB with their OWN new driver):
1) add XLP HI emitters
2) lengthen and thin out tube for 21700 fit
3) open driver up to 20mm when adding more heat sink into the currently HEAVY head
4) offer the C8A clicky tail as an option (they lego with a flipped tube currently- I WELL KNOW!)
I’d buy hosts for sure, and maybe a few final lights (especially IF they run with XHP35 HIs and a new driver— I LIKE Sofirn factory drivers like the C8A and SP10b- they are bright and efficient).
The more the new model legos with the old- the better for modding current toys
My vote goes for 21700 because it seems as a future now.
In the following year we will most probably see development of them.
Personally I couldn’t justify throwing 21700 in long 26650 tube, it just doesn’t seem convenient enough and it would be too bulky for pocket carrying, although comfortable to hold.
Having a 18650 as an option to throw in a 21700 tube seems more reasonable to me and cheap alternative.
Btw imagine C8F with 30T
Adding to my vote above, I join the “let’s add fins” crowd.
Also, would it be a problem to manufacture 2 different tail caps, one with a switch and one without? It seems like a cheap crowd-pleaser.
Also, regardless whether the final decision turns out to be 21700 or 26650, please make the threads compatible with some light available already to enable parts swapping…