What a good news!!!
IMO, BenQ is a decent reader. There's no reason to limit its speed.
Even though 12x and 16x read test was impossible, 16x quality scan suggests that a good media is absolutely readable at 16x.
@ In terms of reading defected discs, 1620 is very good, but not the best. Believe it or not, my pioneer 105(teac branded) is the best reader in my experience. (But it is also the one who's responsible for most of my not-well burned discs )