I can't believe I just found this thread. I've been using ADD and Mp3tag for years separately.
I made a small tweak to return all the jpg images in the local folder and all subfolders (I keep all original scans in a "scans" folder in the album dir), before it was only returning them if they matched the search and it would not return the subfolders images.
I set AAD to "group by local" and "sort by size" and use a couple select scripts (fanart.tv and local) to "search first"
this way I can rapidly see what I have and what needs to be updated