Hi I did not find there to be an appreciable difference between the late 2013 and new retina iMac when I ran at 1600 x 900 resolution. Both had blurry test. Particularly in the task bar. I also found the retina iMac to have more glare. I was disappointed that the retina iMac did not offer a resolution option of 1280 x 720, which is what I use on my current late 2013 iMac, because of vision issues.