The difference between the Air and the 15" Pro is pretty big. The difference between the Air and the 13" Pro is that the Air comes with ULV processors and canno

The difference between the Air and the 15" Pro is pretty big. The difference between the Air and the 13" Pro is that the Air comes with ULV processors and cannot be configured with 16GB of memory. In my experience, you can do development well enough on an Air (2012 MBA for me), but it's not without complaints. I do a lot of Scala+IntelliJ work, and there the CPU is definitely noticeable a limiting factor. It is not unworkable by any means, but it's noticeable. Also, don't underestimate the added value of a retina display for development. I'm looking to buy a new one somewhere in the next few months, and I'll definitely go for a Pro then. Even if Apple starts making retina Macbook Airs.