As a pro line product, the 16GB is used for hose really RAM intensive applications such as Aperture, Lightroom, Photoshop, and FCPX. I can function at base with 8GB but end up choking the RAM while only running Aperture with Photoshop at the same time. For FCPX, I found I definitely needed more RAM. 16GB gives just enough RAM to really function effectively without huge rendering times.