Have you verified that e.Digital has a patent on a technology called "Write Behind" and whether this particular supposedly patented technology is used in the HD 1213?
The prototype you refer to was from the 2002 CES, not the 2003 CES. You keep referring to a PR that is 1.5 years old and there has been no mention from the company about "Write Behind" since then, not even during the 2003 CES when the final version of the product was displayed. That PR also stated that the device would use VoiceNAV, which is does not.
Are you sure that "Write Behind" has not gone the same way as e.Digital's claim that the Odyssey 1000 was to have a new technology called "Drag n' Rip?"