I don't care if a fan is 25mm or 30mm, both will fit for me. If you feel it's unfair to compare the two, fair enough - find a review with only 30mm fans or ignore the rest of the fans in the comparison that are not 30mm.
Personally I don't mind the comparison, since it's useful to me to know if they will be better when both kinds will fit. I'm currently using Corsair ML120's, so they would be better for me. At the tested speeds, they would move 4-9% more air through a radiator, at noise levels (also tested on a radiator) between 1.5% higher (at the lowest speed) to 4.8% lower (at the highest speed). 2.3% quieter on average.
If Corsair happen to come out with their own 30mm fans too then I'll be interested to see how they perform in comparison.
If you read the review on TechPowerUp carefully, you'll see they mention their exact test setup, which is the same as the one for their DarkSide Gentle Typhoon 1450 RPM Black Edition:
https://www.techpowerup.com/review/darkside-gentle-typhoon-1450-black-edition/4.html
They are testing with a 120mm radiator - the Swiftech MCR120QP. They test them all with the same one to give consistent results.
Yes, they go up to 3000 RPM too, so you could claim they should only be compared against industrial fans. They do have that
capability but the fan has a hardware control to select Hybrid, Performance or Advanced mode. Only the Advanced mode goes up to 3000 RPM, the performance mode only goes to 2000 RPM max (I'd certainly use that mode), and the comparison tables vs other fans only measure up to 1500 RPM!
They came out top of the table on airflow through radiator at 1000, 1250 and 1500 RPM, and 3rd place at 750 RPM. Noise/performance tests have them at the top in all four of those speeds.
Of course 4-9% more performance for (on average) 2.3% less noise isn't a massive difference - not enough for me to warrant replacing my existing fans which work fine - but I'll certainly keep these in mind for the future.