I thinking of upgrading to the MBA Ultimate for increased portability and to enjoy it's design. I currently have a 13" 2009 MBP with 500GB and 8GB Ram. 1) Will I see a speed increase? Will it feel like an upgrade? Will this puppy be fast enough to run applications like Ableton Live ( a more intense version of garage band you might say)? I'm a musician and use the MBP for live shows it does the job very well. 2) Do you think the weight difference will be significant and noticeable? 3) I currently have about 350GB used on my hard drive. This will be an issue going down to 256GB. How do you guys handle this? Is it easy to have your itunes stored on an external? What's the most streamlined way to share data in a household. Thanks! I know it's a lot of questions but I want to make sure this is a good idea!