Looks like quite a few refurbs 2012 Airs on sale on 's site. I'm looking at a 8NB RAM with i7, 256GB SSD. The 2012 refurbs are $400 cheaper than the 2013 equivalent. So is the 2013 worth the premium? We're looking at longer battery life. Maybe slightly faster SSD, but is the $400 extra cost worth it?