This C8 looks different from other C8. How about the performance? A useful friend?
What do you mean? The sizes or the triple reflector?
Exterior and interior
Just counted the votes and the 21700 with dual switch is just a bit ahead of 26650 and single switch at the moment.
The other improvements and changes also counted but it is on Sofirn if they want to change things or not.
I think all your questions are already answered in this thread. Plus there are reviews of the stock light in the forum.
Is 21700 going to be a fad or do we think it will stick around?
I think it will be growing. There are some manufacturers coming out 21700 lights like Acebeam, Manker, Astrolux
It’s not so much the flashlight manufacturers I’m concerned about, it’s the battery companies. I don’t know much about the 21700 battery size. Is that size made by any of the major battery manufacturers? What are some of the best models in that size?
Panasonic is fully making the 21700 size but only for Tesla. (And Tesla are making them too but only for self use)
Other manufacturers are also making cells in the 21700 size. Most are going to be used en ev’s. Power Tool manufacturers are also using this new size. So I don’t see it disappearing for a while.
This thread is a useful can of worms, it will be great if Sofirn comes up with a new light that has a couple of improvements over their current C8F. I would be concerned about the multitude of opinions if they were directly vented to the manufacturer, but with ZozzV6 as the middle man it is no problem. 
Thank you! I like more options and want to push things that way to make happy the most people.
I like the way convoy do this.
I have an idea that If somebody want to build a light not buy complete host. The basic host will be the head and tube and reflector. Then separately you can buy switch tailcap or switchless and MCPCB for XM or XP size leds with the specific centering rings. Or something like this. It depends on them how much they will want to sell the host in parts.
Ah, so they are not as great as I thought. You can get 4800mah capacity, but only 10A continous output or 3000mah capacity and 35A continous output. It just depends on the particular chemical mix they are using. Just like 18650 cells. They really don’t seem to compare to the 26650 which has a good compromise between the two.
But they seem good if you need high capacity in a small light as long as 10A is enough.
It also seems good if you need really high amperage, but don’t need high capacity.
With Efest it have 3700mAh with 35A. I think it is very good.
Most single led lights are good with 10A. Even an SST40 or XP-L2 led.
35A pulse maybe? Certainly not continuous.
I would not believe that rating. The best 3700mah cell is only about 30A. Efest has a reputation of not using accurate specs in the past so I am sceptical.
HKJ measured efests 20700 at 30A and about 2900mah. So maybe their 21700 is about the same 30A, but a little higher capacity?
I need to do more research on these new cell sizes.
I agree with your last sentence. How well would a 4800mah 10A cell work with the stock C8F? It pulls less than 10A, right? So it looks like the 21700 might be a good fit for this particular light.
If your hotrodding it, then maybe a 5000mah 20A Liitokala might be the better choice.
Is all the modding you have been doing cutting in on your pig hunting?
The knurling on the Thorfire C8 is perfect. The medium size battery tube is my goldilocks choice . Dual switch I guess. Come on , you know we will be buying both anyway so make all sizes available.
Due to difficult of shipping battery if 21700 is made please tell Sofirn to sell flashlight with good 21700 battery and charger that can fit it.
I think all af their flashlights available in kit but I will tell them to make sure!