I am requesting a hack that allows you to move a bunch of threads at once, but not all threads. The idea is you search for the threads you want to move, like a regular search. Then the search results is a list of threads and each has a checkbox so you can select if it's one you want to move or not. You should be able to look into the thread to confirm it's one you want to move or not.

What, nobody's going to attempt this? :(

You can do this by date and user in the control panel and still select the threads you want to move...

I have suggested the keyword feature for 2.1.