I am going to buy a 13-inch retina MacBook Pro for my girlfriend today. At first, she was looking at the Air but then she fell for the retina model. In principle, I was going to buy the lower-end version (4 GB, 128 GB) as she will make light use of it, but now I am thinking this configuration is a little puny for such a gorgeous laptop that should last for years. I am thinking of buying the 8 GB, 256 GB instead. Is it worth it, considering the light use (web browsing, emails, word processor)? How long is the lower-end version expected to keep fast with only 4 GB?