When cycling a NIxx battery, the cut off voltage should be 0.8 volts if comparing to factory specifications, not 1 volt. Note that I am not saying that it is save to fly until your batteries drop to that point. However, there is still quite a bit of energy still stored in the battery if you cut it off just as it reaches the 1 volt/cell point. Naturally, the manufacturer wants the mah number to be as high as possible so that is why the specifications are usually based on a cut off voltage of 0.8 volts/cell. Not only that, the rate of discharge needs to be controlled too if comparing to factory specs, do not exceed a discharge rate of 0.33C; any higher and you get lower numbers for total mah. IMHO it is safe to fly down to 1.1 volts/cell.