The BenQ is available in the form of a Plextor PX-740. Who knows what hack company may have rebadged the NEC.
As far as Plextor goes, I prefer my PX-716A... As far as BenQ goes, I'd rather buy BenQ's product than one rebadged by Plextor. However, this has got to be huge for BenQ. Having Plextor put their name on a BenQ product.
In addition to my Plextor PX-716A, I have a BenQ DW1620 Pro... both are fine drives. I do use the Plex more, but I am more of an Audiophile than a movie ripper or maker of my own home video's, but I'm diverse and do it all and the two drives compliment each other in my system.
Have patience. I am looking past the BenQ 1640. I expect greater things from BenQ in time. Pick up a 1620 for now. I think NewEgg.com has them for around $40 U.S.