As gugucom indicated, it won't work for OS X's software RAID. You'd either have to find a better eSATA controller + driver (FakeRAID card) than the RR2642 that was attempted, or skip to a true hardware RAID card.
I'm not sure the details, but it seems to do with the GPT is implemented differently between OS X and Windows, so it can't interact. You need to use separate disks at a minimum (assuming attached to the logic board's SATA ports).