It's a very useful addon, but three problems limit its utility once you have a large number of entries. 1. You can't sort or rearrange items, 2. It has a search window in Organize mode, but you can't search when you're trying to Insert. 3. While inserting, you only see the first fragment of an item. You should be able to see the whole thing when you hover your cursor over it.
Starting with version 6.1, which was just released, reordering of clippings and folders in Clippings Manager using drag and drop will now be saved, and the ordering will be reflected in the Clippings menu.