I have this drive for 1+mth and so far I have no problem writing to any, even cheapest DVD-R/RW and -RAM discs (I dont use + shit, and I dont care about it).
I remember upgrading my previous writer's firmware (GMA-4020B) allowed me to write 1x blanks at 2x. However this drive - being it 4x - doesn't need this kind of upgrade, so:

WHAT EXACTLY ARE THE BENEFITS of upgrading to firmware A300 (vs. A104)?

TIA