I don't know, I tried burning those 4x's at 8x and it seemed to take longer... instead of the the standard 14 minute or so 4x burn, I chose 8x and it showed it stalling, "32 minutes remaning" etc.
I don't know, I have a BenQ DW800A which is a +R only 8x burner.
I'm going to stick to burning the Ritek 4x media at 4x speeds. Also, people flash drives like this so they can burn both +R and -R DVDs but reading all the experiences, burning media at higher speeds and/or flashing drives to burn discs they were not originally made to burn is not something that works all of the time. Yeah, there's people all over saying it works for them, but with hot deals also all over the place, perhaps it's best to just sell the old burner and go for the hardware upgrade...