DVD-RAM has been a standard for a while, in particular for data backups. I think this may in part or whole be due to it doing a verify after write. It is also much more reliable/long lasting, if used with the cartridges.
I’m led to believe that it is also much better for working directly with video editing, unlike +_RW discs. Check out some of the forums that talk about video recoding, such as AVSForum for people who have great opinions of DVD-RAM. As this is the main reason for me to get a DVD burner, it somewhat limits my options.
Other than that, I don’t see the world of DVD-RAM being at the forfront anymore.
Given the seeming difficulties in matching media with drives, and finding/using high quality media, any savings up front will be quickly eaten up by disc costs.