Hi. I've owned a 15" MBP and currently own a 13" rMBP. The 15" MBP had to be squeezed into a book bag when traveling and the 13" rMBP is very portable. With that said, I am much more comfortable with a larger screen in the laptop. I know that the 15" rMBP is slightly smaller than the 15" MBP, but is it more portable? The 15" rMBP clearly has it's benefits and with the corporate discount from my firm, the price tag for the 15" rMBP with an upgraded RAM is nearly the same as that of the 13" rMBP with upgraded CPU, only about a $100 difference. If anyone owns the 15" rMBP, your response would be much appreciated. Thank you.