Im my experience the burning speed doesnt matter as long as your HD is defragged and your burning onto quality DVDr.
I have found that DVD-R (with G04 dye) never fail, skip or have any play back issues.
This is with a A05 burner at x4 and a 30003 ps2.
DVD+R are a different story.... some work , most dont. -R all the way for me.
PS2 - Pal 30003 - Fliptop - 250gb Maxtor
PC - Vapochill XE (-22 Deg C) with some other stuff
GBASP with 1g F2A Ultra
DS with nothing yet
and a GameCube (ask the wife why!)