Studio II Upgrade with Blue or Black Caviar disks?

I am planning to replace the 2x500GB drivers in my Studio II 1TB HD with 2x2TB drives. The WD site says that the drives can accept WD Caviar drives only, but I am wondering if I can use the blue or black drives for higher speed? Or, do these drives only support Caviar Green?

I would try the Caviar Green since they are more quiet you will not get that much heat and activity of two drives working simultaneously.