It's probably like the Nu DDW-081 and 082. The drives were identical, but ones that were "better" got sold as the 082.
there are simply not many companies left who consider their reputation as the most valuable asset; benq isn't one of that honorable companies. if 1600 could not perform as good as 1620, then benq shouldn't have claimed or released 1620 upgrade firmware
speaking of quality control i ran across the bad 108 & 712 not to mention this lousy 1600. strangely my bad 108 could not burn +r correctly while my replacement can do. for the bad 712, i had a rare made in japan unit & so was my bad 108. it seems like "made in japan" means nothing anymore
maybe, i can earn another bitter man of the month award
thanks for info folks....i will just return my 1600 to the store since it hasn't passed 30 days return period