I apologise forthe comparisonbeing a little tounge in cheek,but rotor design and production in Asia is limited to a couple of factories. Take the photo below of the plastic rotors for example, one rotor is supplied by Skyworld in Taiwan, the other by Lander inChina who claims intellectual property rights. Lookthe samehuh! They even have the same factory stamp inside the molding Compare the basic blade designs of all the rotors below, very similar.

From my experienceyou need to take most asian factory claims with a grain of salt until you actually try the gear. 3 years of testing? Simple fluid dynamic design would have done this rotor in 3 weeks, there are some classic mistakes in their theory too, they claim to have closed the blade to housing gap to much closer tolerances than other fans, thats great, problem is there is turbulence at the blade tips and having a gap is actually a good thing! Up to 1mm is acceptable for fans up to 70mm in diameter,1.5mm for 90mm up. This makes no impact on performance at all.