its all on the media. a little to do with the drive also.
heres an example
taiyo yuden 4x dvd-r burns better at 4x than at 1 or 2x.
princo 4x dvd-r burns better at 2x than both 4x and 1x.
its all the media. higher quality media is better at a wider range of speeds though.
You could argue that some burners are more compatible with other media. but in the end of the day, TY is good with all burners.
BTW, i doubt we will even see 16x dvd writers. maybe 10x or 12x. but not 16x. hell, they can barely make 8x media at the moment. I havent seen any in australia. i doubt they will even make 12x dvd writers.