I have found this thread which suggests that others are doing this as well.
http://moodle.org/mod/forum/discuss.php?d=62201
Without nasty side effects.
and probably definite confirmation here
http://moodle.org/mod/forum/discuss.php?d=2477
Courses and course formats
Removed Topics - Hidding things.
This discussion has been locked so you can no longer reply to it.