OP here. It looks like you have it. Its search is lovely, its interface is iTunes-esque, it imports iTunes libraries, it organizes files.

It also just crashed on me during import, but I'm going to give it a go. Thank you!

Does Quod Libet support two panes side-by-side like this, a la iTunes? [List: Music library/Playlists/Smart Playlists] [Contents of item selected on the left]

Beware of Miro. Even though they're an open-source project, their default installer comes bundled with various 'revenue-enhancing' toolbars. The main app seems designed to drive revenue to Miro, too.

Actually, I've been using iTunes to manage my mostly-pirated 250GB MP3 collection. I just don't want to run software that contains code for monetizing me when I don't want to be. Even Amarok tries to push you into using proprietary streaming services, which is the music player version of Ubuntu' including Amazon in the Dash View- and don't get me started on Miro. So much hidden bundleware and added "services".