I posted the same kind of results with my 451S and 1693 a while back. I get good scans from the BenQ....but not so good from Liteon or NEC. This is ONLY with TYG02 burned in my BenQ. I no longer trust my BenQ scans of it's own burns. I have not seen this anomoly with any other media burned in my BenQ.
My feeling is the BenQ is a little off with it's TY write and read strats....but that's just a guess.
TYG02 burned in the NEC3500, 2500, 3450, LG4163 and 1693 scan fairly consistently in all drives. The LG4163 and 3500 have the best overall scan consistency amongst my scanning drives. I wonder if not being able to scan plays a part......hmmmmm, something to ponder. Makes you think that perhaps scanning deficiencies cause techs to make firmware adjustments that aren't necessarily for the best.