I received my new iMac yesterday and I'm truly excited about the speed at which it navigated through my iPhoto library when on the hard drive. I have the 1TB fusion drive and know that at some point I'll need to move it to an external drive. I'm hoping for some advice! 1) Can I get the speed I'm experiencing with the fusion drive from an external drive that won't break the bank? I've been shopping around for Thunderbolt SSD drives but they're rather expensive. Is USB3 comparable if it is SSD? 2) I'd love to place my iPhoto and Lightroom library on this external drive. Can I set it up to backup to my TimeMachine backup if it's external? I tried to select a drive once in the 'excluded drives' section of TM, but the drive wasn't selectable. Any help I can get is greatly appreciated!