I'm unhappy with Fusion performance. I've considered selling this (Late 2012) iMac and upgrading to one with straight SSD, but with new iMacs potentially around the corner that seems like a bad move. I am considering the Lacie 1TB Thunderbolt SSD as a stopgap until we see new iMacs. Is it possible to boot from software raid on an external disk? I don't want to split the raid, that would halve the performance and defeat my goals. I haven't been able to get a straight answer on this anywhere.