Last week I flashed the firmware on my NEC 3520a from 1.04 to 3.04 and updated Nero from 6.6.08a to 6.6.012 and was surprised by the considerable improvement to burning quality. I had been rather disappointed with the unit I had, and suspected that I'd been sold a lemon, but these updates have solved all the problems. Take a look at these two quality tests - one is of Imation 8x DVD+R (BPI dye) before update and firmware flash, the other is a disk from a bit further down the same pack of disks I burned last night (both burned at 4X, tested at 5X). Note that both burns seem to be representative of the general burning quality before and after updates. I have yet to try ripping DVD-ROM, so I don't know if this has also been improved.
So what do you think? Is it just the variable quality of the DVD blanks? Or is it the Nero update or the firmware flash? The bad burns show no obvious signs of patchiness of dye or any other flaws.