I maxed everything for the retina iMac except the hard drive and the RAM. My order is already processed by Apple and is on its way to my house. But I start to fear that my decision to only order 256GB SSD will be problematic in the future. The reason why I decided to go with the 256GB SSD is because I have a late 2013 Retina MBP with 500GB SSD, I realized that I never used more than 60GB, so I start to ask myself why do I need a bigger volume in my new retina iMac. And if I need one, I can buy an external HD and hook it up using USB 3.0 or the thunderbolt. Please tell me if there will be any unforeseen circumstances that I will need more than 256GB of HD to make the retina iMac functions at its best?