Ok - I'm replacing my 2009 iMac which is dogging right now. I'm less concerned about screen size since I can hook it up to an external monitor whenever I need to. But I'm more "concerned" with performance. IE the 13" dual core vs 15" quad core. The "labor intensive" software I use are: Photoshop - for retouching photos. Nothing heavy. Not a professional - a hobbyist. Aperture - Organizing photos/collections (at least for now - no desire to switch to iPhoto.. might consider lightroom. I have thousands of photos on an external drive FCPX - mostly editing short videos - not too complicated - from my cell phone, Canon T3i or Ricoh Theta S Microsoft Office - word and not-too-complicated presentations iTunes - I have ~800 movies and 14K tracks that I have on a small external drive and use it to power Apple TV when I want to watch something from my collection Keeping in mind that my iMac is from 2009 and has 4gb memory.. I'm thinking that performance is going to be exponentially better regardless - but was looking for thoughts and insights... thanks!