Roger, nice experimental science, I look forward to more quality research.
Your theory is extremely biased. You prove your point by essentially saying "all else being equal, all is equal" Then you imply a couple times that the jet diameter of the Soto is larger. (So you can bash Soto for high CO) Do you know how much bigger diameter the Soto jet is compared to other stoves? Obviously, for a given jet pressure P, the jet with a larger diameter hole will at least partially live up to the marketing hype (of being hotter).
You also say: "The pressure regulator will only work while the canister pressure is high enough: it has to be a fair bit above P to be able to regulate."
How much is "fair" in your opinion. Does a needle valve need more than "fair" or less than "fair" to deliver the same flow with and outlet of P?
Did you "basically" blow into the Soto stove fitting and a needle valve stove fitting with both set for max flow? Maybe, I'm not the experimentalist you are, but I have more respect for the "face of basic physics".
btw, I would not be surprised if the Soto has a slightly less than a 2x advantage at cold temperatures, but slandering new people, Backpacker Magazine?, is not additional data. Also, Soto only claims a specific advantage between 0 C and -5C, so the advantage probably drops off rapidly outside this range. Although the range is small, many of us would like a prompt warm dinner in these conditions.