Hmmm.... I have heard that Savox are more prone to causing brown-outs than an all-things-equal servo from most other mfg... My 20KG cheapo DS3218 servo is specced at:
"Stall Torque (5V): 19 kg/cm (263.8oz/in) Stall Torque (6.8V): 21.5 kg/cm (298.5 oz/in) Speed : 0.16 sec/60°(5V) / 0.14 sec/60°(6.8V) Operating Voltage: 4.8 ~ 6.8 DC Volts"
and is silent and performs without any issues running off of 6.0v. At $18 and change including a (slightly too thick) aluminum servo horn, I am very happy with it.
I suppose if it has a flaw, it's that it's somewhat slower in response than most - but for the dough, can't complain!
I'll likely be picking up a Hudy servo horn to correct some suspension travel issues caused partly by such an overbuilt servo arm, however.
I can reuse that horn in another rig, though - it's a clamping type and very strong.
I also run those servos. I have been very happy with them. My friend's TRX4 servo died, so we put my spare DS3218 in and he was impressed by it. He swapped it for a Savox 1211SG and actually said he felt the DS3218 seemed stronger.