Well, DVD-R and DVD+R are faster to write on than DVD RAM. If you do WriteOnce, you can do perfect backups on + or - media under 15mins. What else one would want? Make a HD out of a DVD? Nah, come on. If you want HD, then buy a HD, they are so cheap now and price per gigabyte is MUCH lower than DVD RAM discs have (the ratio).
If RAM media will once be as cheap as +/- then I will look into it but now it is OVERPRICED. As I said, want quick backups and etc, get a 200GB drive.
1 disc of RAM (5GB) is about $10. Then for $100 you can buy 50GB of space. If you buy HD, you can buy 160GB of space and UDMA 100/133 transfers. No brainer.