Sandal, basically yes. The power output is higher by 25%, the speed is increased by 25% which should mean that the power draw of a 5 cell pack is 25% higher than a 4 cell pack. In balance, the flying time should be the same. The only exception to this is if the higher voltage reduces the dead-band of the servo. Then all bets are off.
Originally posted by sandal
Geistware;
are you saying that the servos work harder, but shorter time intervals, making the current draw equal to a 4-cell pack? That is VERY interesting. I think you're right, but I guess it depends on flying too. If it is a fast airplane where you pull hard on the elevator through the turns, I think the total current will be higher for the 5-cell pack, because the servos are pushed hard. But with a "normal" airplane with gentle flying, your theory seems correct to me. It would have been great to use some sort of computer measuring equipment to log the current draw to a file and print the numbers. Then we could see not only which pack lasts longer, but also how different manoeuvres affect current draw.