Release date for rebadged drives firmware like Sony 810A/-R has nothing to do with date when latest retail DW1640 firmware was released. It's a known pattern (fact) that Sony (and other OEM's/rebadges) being quite slow when it comes to firmware updates.
And one more thing to consider, how do we know this is an update related to DW1640? It might be some old update for 1650 as well...
I've been running my 1640 on Sony firmware with good results. QSuite? Most functions will work but SolidBurn doesn't seem to be supported, although I'm not that sure about that.
If you are happy with your "@Sony" burns then stay with that.
As BenQ freaks maybe we are too colored, liking all the bells and whistles just for the fun of it.
But then, in the end it's your choice.