Somebody said that with a RAID 1 drive, 4TB will be 2TB of storage, but if the controller goes bad, then the whole drive will go bad -- unless WD can send you a new enclosure? (stated in http://www.amazon.com/Western-Digital-Book-Studio-WDH2Q40000N/dp/B002BH3ZCU/ref=sr_1_1?ie=UTF8&s=electronics&qid=1277567998&sr=1-1 )
So is it just better to buy 2 drives -- each one 2TB, and use SyncToy to sync them up by using mirroring? There will be two power adapters then...
Total cost: $260 plus more electricity probably
It also sounded good to buy RAID 5, which I heard, with 4 of 2TB drives, you get 6TB of capacity, not 4TB. But the WD RAID 5 drive on Amazon.com also has bad reviews