I've also (occassionally) have experienced a seemingly successful move of listing between folders and gone back later to find it wasn't moved. It's ususally when I've selected to move a group of them, but have never figured-out the exact cause of the failure.
Difference between the Saved Listing and Closed is more simple than you might guess. Saved Listings are TRUELY SAVED AT AUCTIVA and you can edit them in the one-page listing editor. Closed Listings are more a tracking of status, and aren't really stored separately. So, there are essentially different types of folders for different functions. Note, you can also have image folders. When you want to SAVE a closed listing, you IMPORT the listing to the Imported Listings folder, which is a Saved Listings (type) folder.....yes, you are reading that correct.
Interestingly enough, I too use the Folders to denote progress in the creation and listing process. I think the methods you use are whatever helps you get the job done best.
Danno