Just got a 2018 i5 13", upgrading from a 2013 RMBP, and I'm loving it a ton. At the same time, I'm considering swapping it for a 15" as I'm feeling that the larger screen size would be worth the slightly increased weight, particularly now that the newer design is lighter overall. I don't especially need the GPU, but I wonder if its inclusion would make the 15" models run hotter than their 13" siblings? My 13" barely gets warm and I love it. Also, would the battery life be less on the larger machine?