I just got back from Best Buy with a WD3TB My Book for $199. Since I could not find the OEM drive, and the My Book is cheaper anyway, I thought I would just take it apart for the single drive. I will post more as I complete more use cases, including the storage pool for WHS v1 with Diehard helping me.
Below are the ATTO stats:
WD 3TB over USB 3.0
WD 3TB over SATA (installed in PC)
WD 3TB in plain Windows 7 Home Premium system as GPT with full space allocation