Azureus has a feature where files are moved to another directory after the torrent is removed.

I would like Ktorrent to consider implementing a feature where the torrent data files are moved to a new directory after seeding has been completed. This way I can look at a certain directory and know that the files in it are no longer being shared so can back them up and remove them from the hard drive without inconveniencing peers unnecessarily.

Well this won't be added in this version, but George may consider it in the upcoming kde4 port.

But what I do is when the torrent is finished seeding I move it myself through "Set download location" and then remove it from ktorrent.

I'm join to bassmadrigal ask. Such "move after seeding" function is very helpful and used also in uTorrent (mine the best windows client). I believe that mentioned function is just a copy "move after downloading" part of program code.

AFAIR, they have mentioned several times already that they will give plenty of options of what you can do when it's finished downloading, etc.
What would really rock, though, is some kind of scripting manager, like Amarok has, which would allow for easy extensibility, with some hooks for when downloads are stalled, finished, etc.