Alex, I think you're right. The lumens are at about 824. I base this on the increase in throw. I have compared the throw of all my flashlights in a field with measured fence posts. This method easily gives a good measure of relative throw among all the flashlights. Since I have published throw numbers for most of them, I can estimate the throw pretty well of any that stand out.
My S200C2vn definitely stands out and my throw estimate is 157,000 lux, or 800 meters. Selfbuilt's published lumen was 770 with 137,000 lux, or 740 meters of throw of the early XPG2 version. So if the lumens increased at the same percentage as the throw increased, then it must be putting out about 824 lumen.
All very amateurish but it confirms your estimate. Having a field with fence posts or utility poles spaced at a constant interval makes a good laboratory for measuring relative throw. All you need to do is count the number of poles you can see and multiply by the spacing. Then correlate your numbers with published throws. It is then easy to estimate throw for any lights you don't have data for.