So far so good! All 3 of mine center well and are very quick and strong just on an Rx pack. I'm sure they will perform well once they are fed with 5.5v and a good amp flow. Only down side is they are very noisy and chattery, I generally expect this with D/MG servos but it has been a little louder that I would expect. Can't wait to see how they fly.
I ordered three for my 500. Very nice servos. Good torque, smooth and quite fast. Setup very nice, only a few percent on travel adjust to level the swash. Going to fly when the rain stops, so I will update after that.
I also have the same model tail servo running at 4.8 volts and flown it for a while. Very fast and smooth. That is why I got these when HK started carrying them. I wish HK would stock more Blue Arrow servos such as the 450 size. Quite impressed so far.