I used Verbatim DVD-R, TDK DVD+R and some TraxData media.
Whenever I go for 8x burn, I have problems with burn quality.
I tired FW: CS02 (not modified), CS09 (not modified) and now CS0P (modified with recomended strategies with latest OmniPathcer).
Still, it didn't help.
So I'm forced to write at 4x all the time if I want a good burn quality.
Maybe it has something to do with my PC in general: Abit BE6 mainboard (BX chipset), Celeron 950 MHz. Not sure. Maybe.
I use Nero as burning SW. I don't notice any buffer problems during burning.