I have Convoy M21A SFT 40 6 amps, Convoy L21B SFT40 8 amps and Sofirn C8G SST40.
Last week I go with my two friends to test throw of thi 3 flashlights and we found dark straight road which have 700 meters straight lenght between two curves.
Night was dark without moon and we test it in way that one of us turned on the lamps and illuminated the road from the starting bend on road, and the other two moved away and measured the light intensity with the photographic light meter application on a mobile android phone. We took a notebook with a handwritten text and went to the limit where the text could be clearly read and then measured the intensity of the incident light on a light meter in order to compare the intensity of the light evenly. The light meter app detects the lowest light level of 1ev at a simulated sensitivity of 25 ASA and that was the limit at which the text could be easily read. Sofirn C8G had the shortest range of approximately 450 meters. Convoy M21A without problems 650 to 700 meters, which is the maximum distance that was available to us before the bend in the road begins, and Convoy L21B at that distance has a much stronger intensity and direction of light and, according to our estimation, has a greater range by at least 200 to 250 meters of light from the M21A. I think that of these 3 lamps, the Convoy M21A is the most usable in all situations because it is more compact in size than the L21B and provides more peripheral lighting, and the 6 amp driver also provides a slightly longer battery life.
Sofirn has a much worse driver and the light intensity is less regulated in relation to the voltage drop when compared to these two Convoy lamps. Discharged battery that cannot start the turbo mode in the sofirn lamp, when inserted in the convoy lamp starts the 100% mode with a visible difference compared to the 35% mode.