I hope my english is good enough for this:
first let me say, that this is an interesting thread! I found it when I was searching for possibilities to change the location of wikis and websites I created within a course.
Actually I use moodle for organizing my writing work. for example I use moodle as a taskplaner in the calendar-view. Or I organize my thinking about "planning courses" by using a WIKI etc.
Because of this usage of Moodle-Features and -courses my problem of reorganizing the existing bits of work (tasks, WIKIS, Websites etc) to another Course (like from the Course "Planning" to the "Textwriting" Course) might be special. I hope you wouldn't find this too odd, since moodle is normally thoght of as a teaching or learning platform
So from my point of view, it would be great if all activities could be copyable/movable. It would increase the hidden power of moodle as a kind of virtual desktop on which one can organize work in a very useful way!!!
(Add a calculator or even something like Excel and this thing would be unstopable ;o) )
After all, it's your decision ... and I can not imagine the work that must be done to solve the problems you discussed earlier. But, as others said before, thank you for sharing! It would be a great innovation if only some of the functions would work!