Unless I'm very much mistaken, you can't bit set DVD-dash media, only DVD-plus. I believe the book type is stamped on DVD-dash media, so it's not something the drive can change.
Personally, I'm using DVD+RW for rewritable (which gives me the advantages of the plus format), and DVD-R for write once. I really need to be able to read the discs I've written with a Toshiba SD-R2102 in an old laptop, which won't read DVD-plus media. I daren't try a firmware upgrade - too many of those drives have been lost trying to upgrade them, and I think it's such an old hardware revision that there probably isn't any firmware capable of reading DVD-plus media. However, I don't have the capability of bit setting on DVD-plus media to see whether the old Toshiba combo drive will read it if the book type is DVD-ROM.