I like these fans (Lian Li), I use 2 pairs of 3 on my radiators, they replaced the 120mm Noctua fans i had for years before them and I do see a small difference in performance. (I changed them for wire management purposes.) These fan blades are smaller than a standard fan blade because they need room to route the interconnects and conductors through the chassis of the fans. It appears Phanteks had to shrink their blades for the same reason, and i think that's the reason for the reduction in performance. I can live with it because I have more than enough head room, I'm only cooling my CPU with my loop...
I hope Noctua finds a way to do this without sacrificing blade size. and without getting sued. ; )