Feeling constrained on the 13" for design and coding long periods of time and the UI lag under load and with an external display is bothersome. Im looking to trade for a 15" with dgpu this weekend. I know the 15" is more powerful but my other questions are. Is the 15" screen comfortabe/usable at 1920x1200? What does it take to get the 15" hot or blowing loud? How many displays before feeling a drop in performance? Does the battery feel better or worse than the advertised 8hours? Is it comfortable to use on the couch or in bed? Is the gpu switch flicker across the board or isolated cases? Is the gfxStatus app reliable for disabling gpu when on battery? Thanks to anyone to answers any of my questions.