I can't see toting around a single CD, let alone a few or book of them like I did fifteen years ago, when you can use a thumb drive, or even better SD card that holds at least 2 gigs. (Some units apparently will only handle 2gb cards.)
In any case, I went for the last in the list, it was shipped today. Not many reviews, but all were mainly positive, and considering it was originally $250 (on rollback right now, maybe originally too much for the Wallie crowd for car stereo), it might be a really good deal. (Also has bluetooth, which might be cool.) I'll holler when I get everything in and running.