To be honest, I think RiDisc media has gone real downhill. I have some 8x ones and towards the edge of the disc, they just don't burn. There are real big gaps like thumb marks on the edges of the discs all around the circumference about 1cm apart - even when the disc is spotless. Really poor stuff IMHO.
So I got some DataLifePLUS 8x DVD-R and I've used 3 so far - all of them were over the 4.4GB mark and all are perfect