Already decided to buy the new 13" rMBP with 16GB and the 256GB hard drive. But now I'm having trouble deciding on the processor. Is the i7 upgrade worth it? With my student discount it is $270 more than the base i5-4238U (2.4gHz). My concern is that the base processor will still struggle to power the Retina display, even with the upgrade to Haswell. Are my worries unfounded?