Drives and RAID
Here is the low down. If you want SAS 15K drives you need the RAID card. The RAID will accept SAS (serial attached SCSI) or SATA drives. The "Green" 1TB drives from Western Digital are slowed down spindle to save power thus "green" these are not performance drives, just 1TB storage. If you want performance then the RAID card and SAS drives it the way to do it.
If you want bulk storage thenSATA and no RAID card, although you can increase the performance of the SATA drives with the RAID card.
The RAID card also offers protection for drive failure when setup in RAID5 mode.
You choose what you want. Apple
did lower the price on the RAID card to $800. I am thinking of making that buy now.