YMMV but I'm using an Air as my main dev machine at the moment. I bought it just because I need a mac for a few things but I seem to have ended up using it all

YMMV but I'm using an Air as my main dev machine at the moment. I bought it just because I need a mac for a few things but I seem to have ended up using it all the time. I'm used to having very small laptops though. I would say you definitely need the 128GB version, I originally partitioned mine into two 64GB partitions (I was going to put Ubuntu on the other which turned out to be very hard, but that's another story) and found that the 64GB filled up from just the OS plus the applications I use for development. Right now I've got it plugged into a huge cinema display (which I have on loan for 6 months, it's very nice) but I have also used it quite a lot as a laptop. I'm mostly writing Python here, so no long compiles. I imagine that would be a killer if you were working on C++ projects...