Heard of that new _external_ GPU? USB 2. No Mac compatibility so far, but certainly an idea for the future. You could add that when playing games and leave it at home if you just want to work without the added bulk. Now I don't find the link, but Asus has one.
I find it hard to believe that it runs smoothly with the settings all the way up, when I was looking at the benchmark tests for games they were pretty low.