It's still the same quality as a dvd9, if not the convenience.
Again...what the hell does that mean? What is the same quality of a DVD9? That phrase itself means nothing. Everything depends on the original transfer, bitrate and how much bitspace is used on the disc. A properly formatted dual-layer disc will always be much better than a single layer disc becuase it has DOUBLE the amount of space. You can't say that a single layer disc has the same quality as a dual layer because it doesn't. It's simple numbers. it's impossible. Maybe to your eye, you can't see a difference. But I guarantee you that if you blow that image up and do a comparison, you'll see a difference.