I just did a quick little test 1S vs 2S on two of my C01S lights.
The high mode is the same brightness on both 1x AAA and 2x AAA (within margin of error on my crude test setup).
The low mode on the other hand is more than 4 times as bright on 2 vs 1 AAA.
Thanks for your input on this Noir! Well, I guess it won’t worth the trouble trying to change the driver from one light to the other…
I’ll keep it as it is, both of them!
Thanks again 
So anyone have ideas if sofirn will make a C01S with middle mode? I’m really interested in this light. The only thing stopping me is there are only low and high. I’ll buy a few if they add middle mode too. Nite useful for me.
Apart from flashlights that have adjustable user interfaces (like biscotti) normally that kind of wishes are a bit futile because there is no user interface that will satisfy all and a manufacturer simply chooses one that seems popular enough, in this case 2 modes, and that is the end of it. But by chance, Lux-Perpetua and Sofirn are working on a red version of the C01S that will have a 3-mode interface (even with 2 mode groups, low-to-high and high-to-low), so the driver is already there. Perhaps you can request Sofirn to make normal versions of the C01S with that driver, or you may be able to swap the led of one from red to white?
I’m not well versed in led swapping.
Where do usually people request for this kind of stuff? Any thread that people use here that sofirn regularly read? As sofirn do listen to customer sometime, at least compared to other manufacturer.
There’s a thread I originally set up with the intention to focus essential communication between BLF and Sofirn.
The general Sofirn development thread
Everyone is encouraged to post his/her ideas, suggestions, questions regarding Sofirn flashlights there. I know that Barry (Sofirn) is reading our input from time to time and appreciates our thoughts. Some of BLF’s ideas were already incorporated in final products.
Concerning C01S in particular, the odds are not too bad that the C01R UI (2 mode groups with 3 brightness levels) could also be incorporated in future batches of C01S. I have been talking to Barry about this topic already but changes like these require the right proportion between costs and benefits (= enough demand by customers). The new driver as in C01R is slightly more expensive.
I am not sure if the driver of C01R, programmed to work efficiently with a low forward voltage XP-E2 photo red emitter, will work properly with an SST-20 LED.
I have both the C01 and the C01S, and like them both. I’m not sure I would go for a three mode C01S. If I want three modes I have several Tool AA 2.0s that I can use that aren’t all that much larger. Granted, it’s not likely that anyone would put a Tool on a key chain, but since I don’t own one of those (keychain that is) it’s a moot point with me.
For me, whichever way this process goes, it has to be high CRI. That is the kicker for me. Since my first High CRI light I have been hooked, and have bought nothing else since then. I am perfectly willing to accept the slight lumen drop to get the much greater color rendition.
Also, I just want to thank you Lux-Perpetua for all your efforts and assistance here, and thank Sofirn for being open to working with us to provide these wonderful small lights.
I’d like have switch tail version of this light,still 1xAAA but 3 modes(no strobe/sos) and support for both types battery.Short total lenght
A switch tail would certainly increase the length of C01S. I am afraid that a tailclicky version would require a new driver or at least some firmware changes (clicks instead turns). The same would possibly apply to the 10440 (3.6V) battery support. This would require Sofirn to develop a complex boost/buck driver for both battery types. The sales margin of this little keychain light is not very high, so it takes a considerable volume of sold units to be profitable.
I am not aware of Sofirn‘s sales strategy for C01S but I could imagine that they will try to use as much common parts as possible for future variations of this light, i.e. same driver architecture, same host design, same UI, a universal manual for all variations, etc..
With the new driver of C01R (for emitters with low Vf) maybe there’s a chance that Sofirn will try testing Osram‘s CSLNM1.TG (a.k.a. „White Flat“) or LG‘s LEUVA33W70RL00 365nm UV LED in this host. However, it would require to use different lenses/optics and I don’t know if it’s worth the effort, see reasons above.
If it’s solely for enjoyment purpose, niche hobbyists purpose then 2 mode, or one mode is already good enough.
However if you want to go into the realm of usefulness, middle mode just adds more capabilities.
Of course the solution of buying another light is a kind of solution for the light addicted person.
The only reason for three modes in a light this small is a moon mode imo. But this adds a problem: If needed, moon mode must be accessible 100% reliably, and this is not the case with twisties in general. My C01S’, and I have many, offer a good chance to jump to an unwanted mode when tighten the head.
4 hours vs 30 min for me. So real middle mode vs just adding moonlight to the low and high. Ambient lighting is better than moonlight in my environment most of the time.
Others may differ.
Driver could stay the same, simple twisty lights like this work by cutting the power off while you untwist - just like reverse clickies when you half-press.
That‘s good and might indeed increase the chance of using this driver for a tailclicky version.
Actually, the new UI used in C01R will introduce a real moonlight mode with only 0.5lm (of photo red light).
why are these not sold on amazon ?
I guess it would add taxes and maybe duty bevor even one piece is sold. That’s why Sofirn asked whether people would buy from there.
I won’t. I bought what I promised to buy directly from china and that’s it.
stuff from china takes ages now during covid19 sadly… i still have an order sent early may from banggood with priority direct mail - still not arrived so normal shipping from china i think would take 2-3months if not more… kinda useless… i rather buy for a few dollars more from a locala amazon but seems not possible 
I made no such experiences. LEDs from Sofirn took a month, ok. Things from int outdoor and kaidomain likewise. Normal. The Jetbeam was here within 10 days or less. Nothing changed for me except Clemence cannot send via economy these days.
Let’s see what arrives first: My C01Rs or those lights at Amazon warehouses.
My order took very long. Also the new site asks me to pay for shipping. I dont mind that but would be nice to offer a few options. I dont like paying 5 dollar for shipping and have to wait 10 weeks for something to arrive…
I wonder if - in times of difficult logistics - it was more cost-effective for Sofirn to send a considerable number of different flashlights into Amazon's distribution channel than waiting for better times with normal shipping duration. I could imagine that more and more customers feel reluctant to buying things they have to wait 2-3 months for. However, in Germany most airlines seem to be soon returning to their standard schedules as of July 2020, so maybe things will be alright in the near future. Anyway, I do not expect the shipping rates to ever drop to their original rates again. I expect a major increase in prices as we can already feel in our everyday's life for food, energy etc..