Bought the Akasa. I had exceeding low expectations so maybe thats the reason I am pleasantly suprised.
At 0% PWMs they spin at 650 RPM and are basically silent. At load they aren't any louder than the stock 92mm GPU fans.
Wished they stop spinning at 0% PWM like the stock fans did, but since they are silent I don't mind and the idle GPU temps are now 27c instead of 57c.