[Al Skierkiewicz]

Doc,
I checked with an NI rep on this issue and although the individual outputs can handle higher current, NI recommends users stay with the 2 ma spec for source current.
The IFI spec of 4 ma and 3 volts sounds just about right as minimums. Typically this will be higher current when energized from a 5 volt driver. Typically I would expect 5-10ma depending on the series resistor that IFI chose in this design.
I didn't have a chance to check the higher current spec earlier but it relates to the maximum input current of an opto-isolator. Anything above that current will destroy the LED inside.
According to TI, the chip maker, the relay output driver of the DSC sinks or sources up to 16ma at 5 volts. The designers of the DSC included a 680 ohm resistor in series with the output to limit the current in case of a dead short.
I agree with Ether on the hobby controller PWM outputs.