My 2012 15 inch rMBP has a defect that makes the lid slightly uneven with the body. Now I can't stand it anymore and I want to sell it and buy a new Air: 1. Can the Air drive the TBD as fluidly as the rMBP can? (Please say no.) 2. Does 4GB vs 8GB make a difference, especially when the machine has a very fast SSD (like the new airs)? 3. Can the rMBP be considered more future proof than the Air for web surfing/Civ 5/word processing?