Being able to see a summary of grades for users across Moodle (or at least in courses which they teach) does seem to be missing for teachers and even Managers.
I have noticed ( in moodle 2.2 & 2.3) that the Overview report only allows Admin to "Select a user" and then see moodle wide course grades as below:
The only possible solution I have seen so far is this "Site Wide User Report" tool, although I haven't had chance to try it yet:
Does anyone know why Managers & teachers can't select a user??
All the best,