Update: I went ahead and ordered the low end. It's faster than the early '11 13" MBP I'm using now so seemed like minimal risk. I'm likely to sell it when whatever pro desktop Apple announces in 2013 so should see more than 30% depreciation in as many months. ____ I'm looking at the entry iMac as a stop gap until a pro machine comes out (I'm just a hobbyist but prefer headless machines I can fix & upgrade myself). My idea is to keep non-video data on external USB 3 (7200rpm) drives and video on a Samsung 256GB SSD in USB 3 enclosure. Am I deluding myself that this would be give me better speed than the stock internal 5400 SATA. Or is USB 3 going to bottleneck me to make it not much of an improvement? I don't have any experience with USB 3 yet.