I don't see any reason why it would stack differently than other sources. When you account for other sources of miss chance, elusive target does provide less than 5%. It usually ends up adding between 1-3% depending on your other miss chances, but I don't see any other ED feat of value really. There are some other options, but they are just as lackluster imo. So I would simply value another 1-3% miss chance over the other options.