This plugin is almost exactly what I need - but it doesn't include all the fields I'd like (e.g. "Last modified (grade)"), and the current "Grade" field shows a display grade (e.g. "42 / 100"), which makes it harder to integrate into other data systems than the straight grade value would be.

I've started working on patches to use a plugin pref to set the assignment fields, like the profile fields already are. Hopefully this'll be useful enough to integrate.