Just a quick look at this thread.
--> Doesn't WD say that the Blacks ARE NOT to be used in RAID config?
--> They DO SAY that you are to use the RE4 model specifically for RAID.
I believe this is the case.RE4 look at "Features" -- says raid-specific
Difference between Desktop edition and RAID (Enterprise) edition drives: Look at "Critical" section on this page
NB Specs on Black and RE are the same.
Anyway, if RE are for RAID, then I would suspect to use RE4 as opposed to Greens.