Is a Schottky diode appropriate for reverse polarity protection?

To narrow the focus a bit from an earlier question:

Is a Schottky diode appropriate for reverse polarity protection?

I'd like to prevent mishaps from a user connecting DC power in reverse, but I'd also like as low a voltage drop as possible. Can you explain what the reverse leakage current is and whether it would be a concern or not in this scenario?

The application is a small device that operates on 9-12 volts DC at less than 100 mA.

Edit:

Just as an example, I am expecting users to be able to use 6 AA cell batteries in series, either alkaline or NiMH. In the latter case, the batteries are 1.2V, so the total voltage is only 7.2V. I am using a 5V voltage regulator with a dropout voltage of 1.3V, so therefore my minimum operating voltage is 6.3V. A bias protection diode with 0.7V drop is going to raise that minimum to 7.0V. As the batteries are drained, I expect to dip below the 7.0V requirement very quickly, and therefore not use the full capacity of the batteries efficiently.

If a 0.3V diode is used, the minimum requirement is lowered to 6.6V, which I feel is a better fit for use with NiMH batteries.

Answer

Reverse leakage current would only apply in the opposite polarity case. This is current that is leaking through the semiconductor material when the diode is in the off condition because it is incorrectly biased. Thus in your application, it is not an issue.

However, you are right to be wary of the forward voltage drop. Only you can decide what an acceptable voltage drop is based on what your power source is and the voltage needs of your regulator or power supply are. Since you are buffering your power supply using a voltage regulator, I would guess that a small voltage drop (less than 0.7 V) would be acceptable. As an example, such a voltage drop might be important if the circuit protection was for a analog voltage sensing application instead.