We have a DVD authoring studio, and write very many DVD-R's. We found that although Samsung, Lite-On, Sony, Aopen, Plextor etc. work fine, but only the Pioneer A05/A07/A09 give consistent compatibility with all our client's DVD-Video players. And we prefer the Maxell 8-Speed DVD-(minus)-R discs for them.
The A09 will do dual layer too, but not many DVD-Video players react well at the layer break, only recent Sony players don't seem to problems with these DVD-R9's.
Hope that helps,
RX-Men-8