I have this same question.
WD5000AAVS drive (500GB Caviar Green) in a My Book Premium Edition II 1 TB enclosure.
The manual warns against going away from WDC drives (citing possible data loss), but doesn’t say if the firmware will support a larger drive–e.g. this one over the stock one.
An answer of, “no idea, good luck” is just not sufficient. I would hope that someone from Western Digital Support would look at this and realize that this issue is driving sales and loyalty.
Great question, as this will drive my next two purchases, and probably yours as well.
