I`ll wait to be shouted down, but I don`t think the problem is so much the `type` of disc but the `manufacturer`.
To my knowledge the only difference between any RW and R discs is the ability to rewrite the RW. This eventually will take its toll on the disc and it will fail (much the same as video/audio tapes do). As a result it could be safer to save important data to the R version.
As for manufacturer, this can have a big impact as low quality can affect the ability of a burner (CD or DVD) to give a good result. I found this out when I bought a `bargain` spindle of 100 DVDs and the first four failed!!!!! Fortunately my brother has a different burner so he ended up with a better bargain than me.
Moral - buy better quality for improved reliability.
Hope this helps.