I have 2012 MBA 13 (i7, 512, 8gb). It works fine for me but I keep thinking about upgrade to MBPr 13 (i7, 512, 8gb). The price is not matter at all. My main concern is that I am using my laptops with external display (30") 99% of the time. I will benefit from retina screen on the trips but, on the other hand, MPBr is 0.5 lb heavier. Will I regret the upgrade? What do you think if you moved from MBA to MBPr? Thanks.