I'm currently using a 13" MBA. It's a little bit tight on ram (only 4gig) but it runs plenty fast for rails development. The real joy for me is that the size a

I'm currently using a 13" MBA. It's a little bit tight on ram (only 4gig) but it runs plenty fast for rails development. The real joy for me is that the size and sturdiness of it means I dont think twice about throwing it into my bag before I bike off . . . anywhere. It's always with me so it gets a lot more use than older chunkier laptops that I've owned in the past.