Actually, in addition to the archive attribute (which looks quite promising) there's also this in the RoboCopy help:

/FFT :: assume FAT File Times (2-second granularity).
/DST :: compensate for one-hour DST time differences.

Interesting...



But more on the archive attribute. Is it reliable? As in, is it maintained by Windows itself, getting set from any change, or do I need to rely on individual apps setting it for the files they modify?