Are DVD+R9 (DL = Double Layer) supported?
Yes, it seems to, it will be necessary to test more, but I have already tested a copy of my DVD #1 of “The Return of the King” (long version). Copied on DVD+R DL Verbatim Datalife Plus (Mitsubishi Kagaku Media) 2.4x, burned at 4x with Nero 6.6.0.3. I have ripped the tracks with DVDShrink without compression, keeping all items (menus, etc.) … 7,45 Gb burned. Result: no problem, the DVD is well recognized and played up to the end.