I didn't want to spam the thread so a small list of features I thought of as I was going on a tagging rampage:
1 - Right Click > Remove from Playlist. If I use a playlist as a sub-inbox, say for a label or genre, I have to find the files that have been organised and somewhat manually remove them. I'd love a Ctrl+A > Right Click type option as a fly-out.
2 - Use contents of tag as a variable rather than string. In my case, tracks are going to have "Various Artists" or a single artist as a tag. I'm trying to hunt all the mis-tagged files in an "if <album artist> is not equal to <artist>" auto playlist as a starting point to but it doesn't look like that's supported.
3 - Ability to change the middle-click-on-tag-search from "is" to "contains" or "is xx% similar to" and search all tags, not the clicked category, maybe via shift/alt/ctrl click as a modifier? Its a great feature but it falls over on accents or "feat. xxxxxx" type tags, where the typed search does ignore accents etc.