Good questions but from a purely electrical standpoint current is current and voltage is voltage. So even with digital servos you are faced with the same issue as any other a/c setup. And that is having enough battery capacity to service the servos for x number of flights. You can figure about 33 percent to as much as 50 percent more capacity needed when switching say 5 analog servos to 5 digital servos. That has been my experience on the giant scale planes. So if you normally run say 800 mah pack on a 40 size profile using 4 analog servos (don't count the throttle) and go to 4 digital servos, you may want to use a 1200 mah lipo pack. Keep in mind that a 2-cell lipo produces over 7 volts so after it is regulated down to 5v you have even more capacity than pure mah. Without getting into much math, wattage is the units of available power and watts = amps times voltage. I have no idea about the cs 45 servo!