Yea, was wondering bout the temp settling. I probably didn't give it enough time. As I was writing the post above, was think'n should check dead cold. Think it hit in the 90's after a min or so run on max, then it drops quick to 60's.
I took gChart up on his offer and managed to upgrade my D25 from the original basic 5-levels+hidden modes to a stepless ramping UI.
Thanks to the efforts of gChart, who effectively remapped the original (PIC?) MCU to a similar footprint Attiny MCU (Attiny412), and ported/re-flashed the MCU with TomE/ToyKeeper’s excellent (D4?) RampingIOS see here - the D25 has gone from meh to awesome!
Original UI mode level range, 5-levels from 2.38A to 0.08A (draw at tailcap)
Upgraded RampingIOS range, ramping from 2.38A to 0.01A (draw at tailcap)
In addition to ramping and the exanded level range, the headlamp now has -
- Battery Voltage indicator using blinkies,
- Thermal Management,
- Last-mode-Memory, and
- direct access to both Minimum (long-press from Off) and Maximum (double click) from Off.
This is the upgrade this light really needed. Good work gChart :+1:
Note: For the benefit of anyone attempting this, the switch cover plate is “reverse/left-hand threaded” to open. (Thanks to TomE for the reminder) 
Nice! Just got in the single LED version ($12 shipped from Ali store here), so could do something with the optics now, least a copper MCPCB I hope.
For the double LED previously modded, I sanded down the scratched end cap so now it's smooth alum - scratches still there but not as noticeable - looks better.
Well done, PC! Glad you like it 
What is the result? Is Optics Suitable?
Lent out my light, still waiting to get it back.
I went out and used my D25 a couple nights ago while I applied crabgrass preventer to my nearly 1 acre. It lit up the yard nicely. And with it being mildly cool out, the temp regulation* helped keep things bright but still in check.
*Stock light does not have temp regulation… It gained that after my MCU swap
Was able to fit a couple of 60deg 17mm Yajiameis in mine. Had to sand down the diameter and base of the optics until they fit. Also swapped in some neutral white XML2s. Can’t remember exact tint but probably 4C.
~30 cm from white wall. Nice and floody
In preparation of my review of the D25 I noticed something odd about the beam profile. The spot is darker in the center, seems like a slight donuthole.
Could it be that this is the result of the overlay of two emitter beams, causing areas of erasure and amplification?
Thank you for your reply I also ordered the headlamp. Yesterday at Aliexpress for a great price - US $ 9.44.
Thanks. I ordered one as well. I wonder if it’s the exact same. Looks to be ,but the name is is d10 instead of d25
There are 3 of ’em listed, the D10 (1 emitter/lens), the D25 (2 emitters/lenses), and a zoomie (unno).
Wow, this is a good thread. I wish I had found it earlier.
Someone said earlier that the D25 and D10 had the same driver.
Here is Tom E’s stock D25 driver.
Here is Flail’s stock D10 driver.
Note the dot on the chip.
The pcb layout looks the same. Maybe these are different chips and the dot has a different meaning for each chip? I really don’t know.
Hhmm. The dot should always be pin #1. Maybe a batch of fake MCU got it reversed? Weird...
The U3 labeling is different - maybe the PCB design is different? My pic is not so good, look'n compared, shadows are hiding a couple things 
PCB part just under MCU (between MCU and FET Q1) is different as well. It would be nice to check PCD layout on the back side, but it look like divers are a bit different. I would rather expect the same MCU on both. Used FETs and resistors are different probably due to number of leds used, but I think that schematics might be the same for both. Maybe one of those is just an newer revision.
The pin on the upper right in the driver pics looks like it goes to Batt Neg on both drivers.
Tom’s D25
Flail’s D10
Different revisions
Uh oh. Glad you pointed this out, Jason. Glad I haven’t sent out too many MCU’s… they’ll need to check which version of the driver they have.
Here’s mine (D25) with the MCU removed. It appears to be the same layout as Tom_E’s
Have you guys seen how many names these things are sold under? It's crazy! Sofirn even sells them.
This one with a COB and USB charging looks interesting at under $4 shipped: https://www.aliexpress.com/item/Outdoor-camping-Portable-mini-XPE-COB-LED-Headlamp
FWIW, confirming that my D25 version that worked with your pre-flashed MCU was also - T02-A VER:03.
actually this headlamp is everywhere in China. 77outdoor purchased them to sell after tested by sofirn. That’s it.
Since the D25 has bad UI, I helped sofirn upgrade the model to make it a little bit different if not much better.
It called D25S with 2* SST40 leds 1200LM and different UI: click to turn on/off, press and hold to change brightness levels.
Will be available soon.
Maybe it still won’t be as good as you think it should be. But it’s more usable.
It officially claims 1200LM because the heat sink ability is not that good for more current. You guys can DIY it as you wish.