Hi. As far as processing speed how does a refurbished 11.6-inch MacBook Air 1.7GHz dual-core Intel Core i7, 8GB memory compare to a 13" Retina 2.4GHz with an i5 processor? I know that incremental increases, i.e. 1.7 to 1.9 is not that big a deal. But does does the i7 make a significant difference for every day usage, i.e. writing and web and also for more processor intensive use like Aperture. I ask this with forgetting about the screens for the moment. There's a refurbished Refurbished 11.6-inch MacBook Air 1.7GHz dual-core Intel Core i7 with 8GB memory and 512GB flash storage for essentially the same price as the Retina (8GB/256). Thanks.