I've been using an external SSD plugged into my old clunky 2011 27" and the smaller size iMacs and booting from them as the main drives. I know there are better ways to do it, but as long as I don't open too many tabs at once it seems to work just fine and MILES better than the old spinning HD it came with. My question is this; if I should have to go away for work last minute, and need to take that info with me, can I unplug the external SSD and plug it into my MBPro and boot from it while on the road and basically have my desktop computer with me? Is it that easy? Would anyone know for sure without me unplugging and testing the whole procedure? Thanks in advance! PS: For what it is worth, I got a $15 Sabrent USB 3.0 to SSD /2.5 Inch Sata External Shockproof Aluminum Hard Drive Enclosure and put a cheap 128GB $40 SSD into it and just used the USB connection and booted from it with directions on Google, and OMG my old computer that was too slow to work is FANTASTIC! I highly recommend this cheap short cut if you have a slow regular drive iMac.