They are wider than a STD servo, so fitting isn't great on any car where you can't move a servo post.
They are fast.. But they don't return to neutral.. About 5 degrees off left and right (bought 2 both the same)
Overall - not great
Note - this was with an esprit3 and spektrum 3500 rec so it might justnot be compatible with them. I will try it with an old acoms and see if it's an issue with high response