E-SATA is just as good...And it's the only multiple sata drive option you have on a macbook..
I'd skip the internal drive all together and get an e-sata/raid card for your macbook and do a radi 5 with raptors... This way you have redundancy.
As I said, I run 8 raptors and I haven't had one die yet. They are rock solid in my opinion