I have several of these older but good meters and they all reproduce mirror results and that's a good test.
I do wiggle the probes connections and rel zero the meter before testing, I did see 0.33 change to 0.13 - 0.12 and the light went from pitiful to much better.
A good MX-900 single cell draws 2.2 amps at 4 volts.
My good single cell single XML-l2 draws 2.8 amps from 1 cell ( 4 volts )
This draws 4.9 amps from 4 cells in parallel ( 4 volts ) after my repairing the limiting resistors as it is now.
I think I am right where it's designed to be or just slightly less, it's not 7 times what my good XML-L2 puts out but it is twice as bright, where before it was just even.
Edit-------The video said stock is 35 watts and I am only drawing 20 watts, but his is an earlier model and his limiting resistors are 0.05
I use the dark bathroom lighting up the white ceiling test and I look at the walls to judge room brightness and it is twice the light of the L2, too bad it's not 7 x the brightness. But I know it doesn't work that way, however the leds have plenty left in the tank, the drivers I think may be near their factory limit, I'm not sure, I heard they are 6 amp drivers in this video below.
p.s. I used short 12ga solid copper jumpers to bypass the tail cap switches and get inductive current readings, but I did not have a 3rd hand for the camera, lol.
In this video the guy says the drivers are 6 amp, I see 2 are common to one poll going to the 7 led head on my board, the other chip I think is the control chip for the modes.
I wonder if I could heat sink the chips and lower the limiting resistors some more.
You can skip ahead to 8:00 for the technical.