Im thinking about trading my recently acquired MBP 13 for a MBA 13. I like that its lighter and smaller and more portable. i decided against it at first because of the no optical drive but turns out, i dont really use it. Like ever. I also would like the bigger screen resolution for my studies. I want to know how the 2 compare in terms of real life battery life though. I currently have a Macbook pro 13, 2.4 ghz with 4gb ram, a 128gb SSD. After the SSD, this thing is a killer with a boottime of 13 seconds, shutdown of 2seconds, battery life around 7-8 hours of light browsing or typing and around 4 or 5 hours of heavier use, 3 hours of flash and multimedia. Will the macbook air 13 with 4gb ram have better or equivalent battery life? WHat if I get the ultimate with the 2.13 ghz processor?