I have an application that reads (and writes) SubRip subtitle files. I am now doing a complete rewrite of the code and am stuck with a design decision: Should I use Core Data or not. I understand that Core Data would bring me some benefits, like undo/redo support, which can be rather complex to implement. I've never used Core Data before (except for some playing around) and am not sure whether or not to go all Core Data on my app. Here my question: Should I create my own custom atomic store, use an in-memory-store, adding subtitles from an NSDocument subclass or forget about Core Data entirely? My application is targeted for 10.5, so that is not an argument against creating a custom atomic store. I'd be glad for any advice.