Well, I have to say that the Empeg is so central to my music listening that every time I get a new album or I move/remove a song from my collection, I update just those changes to the player, so it's really not difficult to keep my PC and my car player in synch.
I do moving and removing of songs so rarely that I don't understand why it's such an issue with some people. And when I buy a new album, it's a pretty straightforward thing to add it to the Empeg.
For the people who are so concerned about a full-offline-bidirectional-synch with the player, I have one question: Is most of your collection pirated MP3s from the internet, and that's why you're so concerned about the multitudes of changes on your PC? Because for me, doing just one CD at a time is not a problem.
Even if you do a lot of random internet downloads, simply being a little more organized about it should solve 90 percent of your problem.