Yes, using file system folders and the Photo Library is a powerful workflow. Quite a few people do that. In fact, Nitro has a specific feature that lets you export originals + ratings + edits between the two systems. So you can edit in a Finder folder and then add the original + all the edits to the Photo Library (or vice-versa) – meaning that you can continue editing non-destructively if you like. Of course, you can also just export a finished image to the Photo Library as well.