I am thinking of getting a macbook air, however am torn between the 128GB 11inch model and the equivalent 13inch model. When trying the 11inch out in store it seemed perfect for carrying around and all round portability however I have heard that the battery life isn't great and in real terms 3-4hrs is slightly short as by having to charge it regularly it defies the point of portability. I would like to know what owners of these models think is the best option after having experienced the machine for a while and whether I should instead opt for the 13inch which has a better battery and screen resolution but is not as portable.