I have not run my SG PCB driver down that low to be honest so i dont know, i have swaped out my TF C8 SG PCB driver for another that flashes when it hits 3 volt under load. My old man says the KD C8 i gave him shuts off when the battery is to low but that could be the low voltage cut of on the batteries.
As for what DDM,s i use i use two a Fluke 75 series 2 DMM and a cheap DSE DMM i have compared both to a new fluke my old man has thats way out of my budget and they all read really close to each other.
The batteries i did test on the KD C8 when i first got it was the trustfire flames 2400 mAh they are good for 3 + amp discharge, i since have tested on redilast 2600 mAh with current draw readings with in 0.15 amps of each other.
When i first got my KD C8 you could run it on high for over 85 mins on one battery on a winters night with out it getting it warm, the best current draw test i could get was 1 amp with trustfire flames and 1.25 amps with ultrafire greys they read higher due to voltage sag, i tested 6 bateries and 2 brands of batteries when i first got it and thats the highest current draw readings i could get from all the batteries the average draw was under 1 amp.
After cleaning up the electrics on the driver adding solder to the led wires on the driver side and adding more solder to the brass pill and driver i was getting current draw readings of 1.5 amps then after a while it would settle to 1.36 amps but then it would get warm, if you just let it sit there with no air flow going over it.
Now KD told me the KD C8 is direct drive, but mine had the 2 amp SG PCB driver in it and the replacement driver KD sent me was a 2 amp SG PCB driver, i never bothered to install it, but no matter what i did i could not get it to draw past 1.5 amps at start up aprox 500 OTF, but my old man is happy with it as a work light.
P,s heat makes them drop lumens.