I have a 27" 2010 iMac. Need to upgrade as its slowing down. I was waiting for the recent updates and now ready to purchase. I would like to get the all ssd hard drives, but Apple's pricing is crazy. Current machine is using ~ 800 GB, but a bunch of that is duplicative stuff I can move to external drives. But I still likely need 1 TB of total storage. My question is: can I get away with getting the cheapest ssd drive option (256GB) and then get external ssd storage? Not interested in installing a new hard drive myself. But since its sitting on my desk and not moving, I am okay with getting an external ssd hard drive for the additional storage. I believe the USB 3 or Thunderbolt 2 ports should be fast enough, yes? A 1TB external Samsung SSD is ~ $450 and the upgrade from 256GB to 512GB is additional $300, and up to 1TB is additional $900. Also, is it practical (good idea) to get a high capacity SDXC card (256GB or 512GB) and put that in the back port? Thanks. Appreciate any thoughts.