The export preferences settings do not offer enough variables to make the Export As... function work effectively. I am working on gigantic files which I need to send to a client, scaled down for approval. The Export As... always freezes trying to preview the images, if I can even adjust any of the settings before it starts to lag. The Export Settings are basically useless because they only allow you to change "quality" but don't allow for any scale settings and you're bound to whether or not the Export As dialog freezes when you open it. Legacy settings are also grayed out so that's not an option for a file this large.