Yes, we have both early 2013 base models, 13" is 10-15c cooler. Tested it on the weekend just general browsing here. And that was forcing my 15" to discrete only, otherwise it would have been 15-20c more. My next one will be a 13". 15" gets too hot for sitting on your lap.Does the 13" run a lot cooler than the 15" overall everything being equal.