I'm currently undecided between these 2 models. I already have a 27" iMac (maxed out) Mid 2012 model that I use as my main computer. Looking for a portable laptop for school (Graphic Design major.) Price difference is about $500. For that extra $500, I'm getting a quad core processor, about 2 extra inches of screen space, and Intel Iris Pro Graphics. Other than that, the 13-inch sports the same hard drive and memory and weighs exactly a pound lighter. Any thought on which model I should get?