In this very second, I am at a rewrite of the Map-Editor. I now make very good use of the amazing AJAX technology (aaah.. the possibilities!!

).
In the new version, all changes are written to the database, the moment you make them (click on a square to place an item - BANG!, it's in the database). Whereas earlier, all stuff was written into hidden textfields and then written to the DB when the form was submitted which was _terribly_ slow!
And it also improves the behaviour when you move items. Earlier, if you move a seat which is occupied, the new seat (after movement) will be free again as all entries were deleted and recreated when moved. But now, I actually just update the row and col coordinates in the database. Neat!
I will think of this option too. No worries. Just copy all items, but make all seats free again, yeah?