I just replaced my 2011 Macbook Air with a new Macbook Pro 2.9 GHZ/8gb/512SSD 13" retina. I use my computer on my lap 90% of the time. The Air ran pretty cool, but did get warm when I had a lot of apps open. The new MB Pro runs pretty warm ALL the time. Even just surfing the web it gets almost uncomfortable in my lap. My question is which would run cooler...a 2.9 GHZ/8 GB Macbook Pro 13" retina or a 2.4 GHZ/8 GB Macbook Pro 15"?? I'm not opposed to returning the 13" for the 15" if it runs at a more tolerable temp. I believe I saw a reference somewhere that the 15" with the quad core processor would run cooler that the dual core 13"? Any input? Thanks!