For one, my experience with WD drives since 1999, encompassing several hundred of them, is that they are absolute garbage.
For another, no drive benefits to any degree with a cache over 512kb. You will notice no difference between 8MB and 16MB caches. That is a marketting gimmick. Please see the following article for more details.
http://www.ececs.uc.edu/~oscar/pape...earch="benchmark 8 mb buffer to 16 mb buffer"
In the time I have been dealing with WD, I have RMAed over 30% of them. The only drive that has given me worse luck is Fujitsu. They are also complete crap in mission critical applications such as file servers. They just can't handle the load.
I gave up being a WD Authorized Reseller for that reason. I didn't need the headache. I simply refused to sell them unless the client wanted a Raptor or Caviar RE.