Hi,
There are two ways its better. First the servo power does not go through the receiver bus. This mans that servo high current demands cannot pull the receive bus down to where the recevier will reset. You will find the place where your biggest voltage drop occurs in across the batter connector going into the receiver. The standard R/C connector has a fairly high resistance for a connector. This results in higher voltage drops at higher current. A regulated battery does nothing to help this. Second, we regulate a fixed 5.0V to the receiver from the input (2-cell lithium) and feed that to the recevier so it sees a constant 5.0V irregardless of servo load. The receiver regulator has an additional capacitor on its output to hold the voltage up in case of any spikes on the input to the regulator. Please let me know if you have any other questions.