Yes you can and yes you can raid them but there is no real reason to. After using the air which has basically twice as fast as most ssds I can say that you wont notice a real speed difference if you do a raid and failure is more likely imo. My old sata 2 x25m feels just as fast as the pcie ssd in the new air and just as fast as the much better sata3 ssd in my rmbp