I'm looking for an external Thunderbolt SSD drive that I can use on two iMacs (hopefully). One is my late 2012 27" iMac (13,2) and has a Thunderbolt 1 (10 Gb/sec) port. The other is my Mom's old 2010 21.5" iMac (11,2), however I'm not sure if it has TB fuctionality or it is strictly for Display Port (?). I would like to use it for backups using Carbon Copy Cloner or Super Duper since both are in need of new internal drives. I've thought about going USB, but it looks like both machines are limited to USB 2 at best. I figure I'd get a TB interface because it could be used in the future after the drive upgrades. Any suggestions?