Good start, but needs to emulate what BBCodeXtra used to supply, such as the ability to turn selected lines of text into a BBcode list with just one click, in other words the tags [list][/list] as well as the [*] tags are all added with one click.
Note to other readers, if you go to the forum at phpbb and search for bbCodeInsert, you'll see that someone has ported that Chrome extension to FF, and it is as good as BBCodeXtra. "Edit" would do well to get it, and study it, and do better than it can do ... if you can!
The Search/Replace feature works well in this add-on, and the options to transform text (uppercase, lowercase, capitalize and add tags) are impressive. I agree with the earlier reviewer that the process of adding custom tags can be a bit cumbersome, but once you have the tags configured the way you want them, the set-up time seems worth it.