I already ordered MBP 15" early 2011. The main bay is apple 128SSD. I am planning to buy one more hd for the storage. But what is the difference between with a second hard drive in the Optibay and external drive ??? I mean any difference with the speed ? As I know, Optibay will use sata2. And the external drive will be select FireWire 800... Or any difference I need to concern ? Thx a lottttttttt !