Config.meg is just where the XML and LUA script files get stored once compiled, whcih helps a bit with loading times, and is a bit cleaner. Stuff could be in the unit XML entries and still be in config.meg. There are a few reasons we switched to using the LUA-script based fighter spawns. One is for single-unit retreat, as you said, since in order to allow the script to call back fighters (functionality we can use for other stuff besides SUR, too), it needs to spawn that way. Second is for boarding, like Dave said, so that when a faction captures a ship, we can customize the fighter spawns without needing to swap the ship to a different faction variant. Thirdly, for performance and organization- by having them in the GameObjectLibrary we've created, it means instead of needing 6-7 different variants of the same unit strewn accross the files, which all need to be kept up if we needed to change something, we can have one variant. Having more unit variants significantly increases both load times, and can increase lag on the galactic map.