Well - you can drag & drop from iTunes to any MTP/UMS machine, especially a self-databasing one like the Sony's.
The library integration is what I was looking for. I may not have said I don't like Synctunes, and iTuneMyWalkman is not exactly what I'd like either. I was wondering if there was another alternative as the library shenanigans of trying to use the Mac for certain players and the PC for others is becoming really annoying.
It's a very long story but this is what I have to do right now. I see settling on iTunes for everything as likely a lesser evil in practical terms, despite the Windows software being an order of magnitude better (but not supporting the Touch properly, which I also want to use).