Couple of comments on your post Tony:
1. If you can restore to 'as-new' from the CD then this presumably includes the CDDB database [which is presumably on the 'restoration' CD somewhere?].
Which you then need to update to bring it to the latest version via downloaded updates.
2. While it would make a great centre for all your music files, the same problem that the current users of the Empeg face still arises:
Having ripped all your music (at 256 or whatever rate), you then have a large hard disk stuffed full of files (with 100% correct MP3 tags) which need backing up somehow to protect against disk crashes etc.
I guess you could sit there and feed the unit with CDRs [or CDRWs] to back up the database, but with a 40GB disk thats about 50 or so CDs to back it up [and restoration of said backed up files]. Even at 8x write speed, thats still a lot of CDs to burn and a lot of time to sit there feeding it with blanks.
So my suggestion would be to allow the unit to [somehow] archive its ripped files back to a PC for storage/back up only [rather than for playing on the PC] - although there is no reason why you should not be able to do this either as its your CD you've just ripped so you now should be able to treat the mp3s like any other MP3 file.
Or allow multiple HSX's on the LAN to network to each other and allow you to copy your mp3s from 1 unit to the other.
While some might say this only encourages piracy I can assure you that having ripped 200+ CDs to your HSX the last thing you'll want to do is re-rip them due to a hard disk crash.
[same piracy comments may be said about the ReplayTV show 'sharing' features]
BTW: No-one has said what the USB version supported by the HSX is 1.0? or 2.0?
Also, I can't see any mention anywhere what the supported USB to Ethernet adapters are.
I imagine only a few common brands of these devices will be supported but what brands are they?