With the inbuilt composer it's possible to upload a file and then reference it in markdown.
I see that's not possible in BBCodes Plugin.
One other problem I have encountered is that when I installed the latest version I did not get a BBCode button bar at the top of composer and was unable to submit posts.
Edit: I have now been able to fix that problem and have recreated the steps that causes it.
If you install the BBCodes plugin and deactivate the composer and markdown plugins there is no issue. If you uninstall the composer and markdown plugins then the BBCode plugin seems to have issues. Perhaps it's localised to my installation but maybe others have the issue.