Regarding question about ATRAC3 format, as a recent NetMD purchaser I can tell you (although far from an authority) that support for Sony's NetMD products is a recent addition to RealOne Player (ROP). Sony's NetMD products come "crippled" with OpenMG software, which was (prior to ROP) the only software that would write to the NetMD devices. Now ROP has added support, offering NetMD users another way to save music to MD. See
www.minidisc.org for more info.
OpenMG was basically a media jukebox with added support for copyright protection. Tracks are "checked-out" to your MD player, and must be "checked-in" when you're done listening to them. Although OpenMG recently added support to import MP3 files, loosening the imposed copyright restrictions, the software is still kind of buggy. Since their user audience is so small, they seem unmotivated to improve the software.
I would love to see MJ add NetMD support, but I'm sure Sony and RealNetworks are probably going to be exclusive about the NetMD support. Oh well...
I use ROP for writing to my NetMD player, but I live in fear that they will make this a "subscription" feature in the future. I will NOT pay $120 per year for their software, dang it!