Just finished watching a few Big Muff shootouts and I have to say, that there is nothing particularly definitive, even though folks think there is. Sometimes the Green Russian sounds "warmer" and sometimes it soundsz more fizzy and sizzly.
The thing that drives me nuts about these so-called shootouts is that the BMP is known, and even explicitly described by Mike Matthews in interviews, as highly susceptible to unit-to-unit variation resulting from component tolerances, yet none of these shootouts employ more than one example of any given issue. The assumption the viewer is supposed to draw is that ALL units of such and such an issue sound
exactly like that, and the reality is they won't. They'll certainly sound pretty close, but unless EHX magically started using 1% tolerance components, matching capacitors, and selecting transistors for hfe 20 and 35 years ago, there is going to be unit-to-unit variation, and likely more variation
within an issue than what you hear between the issues ostensibly being compared in the video. And if one thinks that setting all three knobs to the 12:00 position results in all controls set identically, think again. Pot tapers are always approximations of a standard, such that the Tone control on pedal A might actually be 88k and the one on pedal B 104k (both realistic values for a nominal 100k linear pot), with the 12:00 position on pedal A dividing that 88k into 47k on the left side and 41k on the other, and the midpoint on pedal B dividing the 104k into 48k on the left and 56k on the right. I.E. what
looks to be the same setting is not.
There HAVE been changes to the circuit over issues, but other than the op-amp BMP, the basic structure has not changed since the early 70's. I can give you the exact same circuit diagram (just as Kit Rae has) and the only thing that has changed is some of the component values, largely because of the transistors and caps Matthews managed to get a bargain on at that time.
I'm
not saying that none of them sound any different. I'm saying they will not sound
consistently and
predictably different in any way that is not easily compensated for by tweaking an amp tone control or turning a pedal knob a bit this way or that.
Obviously, that's not your fault, and is certainly not a fault of the pedal itself. But there are a lot of myths about the various BMP issues that simply don't hold up particularly well. Until someone makes a video that uses ten randomly obtained copies of each of several different issues, and we can easily hear that there is a"sonic signature" to to a given issue that holds true across all settings of all copies of that issue, that's my story and I'm sticking to it.
I can be stubborn that way.

^)@#