9 DVD+R burning very long

The first tests of the Sony double layer burners, the DRU-700, emphasized a problem which could make it less expected by burning fans.
It takes 45 mn to fill a 8.5 Go data disk. The speed is only 2.4x and the final stage is extremely long.
During the same time, using a 8x burner, it is possible to burn 4 simple layers DVDs. While the DL medias prices are still so high, the simple layer burning still has a rich future.