I have two sets of 599's two Imac planes and they worked very well over the years. The 9930 is very good and I prefer the coreless in servo in the jets, if it fails it won't stay locked over like the brushless servos can.
On the pro or Max size Rebel the 599 for flaps but I've used 9930 on flaps with no issue on my Rebel Pro.
I just ordered six 9930 from Aeropanda yesterday and our Canadian dist would only allow me four servos, kinda sad they limit stock on black Friday sales.