Hello all, I'm really interested in buying a Retina iMac soon. My main use is heavy Lightroom editing and Photoshop (Canon 6D). I also plan on using Final Cut and Adobe Premiere. That said, I am also on a limited budget so I cannot go for the maxed out version. 1. Should I go for 1TB Fusion or 256GB flash? 2. Should I upgrade the CPU or GPU? 3. Besides the resolution difference, is there any other noticeable difference between regular and retina? (Colors and contrast) Thank you all for your input.