I can confirm it works well, we use it to share content (ressources) on several courses.
But, it means that this course (content) is usable by anybody having an account on your Moodle, which isn't always something you really want.
Talking about activities, i don't see how such a thing could be used... because students have to be enroled in course. So, having a state of usable (but not visible on Dashbord) could be helpful.