For those interested in the differences between Analog and Digital servos here is Futaba's take on it.
http://www.futaba-rc.com/servos/digitalservos.pdf
Down at the bottom left there is a picture of what Bob G. described. Many pulses give you the hum/buzz/chirp you hear when using digital servos. Each one of those pulses is telling your servo where to be, chopping it like this keeps the servo right where you think you want it.
Keep in mind Digital servos use more power throughout the day, so if you find yourself drained sooner then you're used to, its probably because of the digital servos. Is it significant? I haven't found it to be so, but during a regatta I will switch My batteries, during a break, to be on the safe side.
Ken