Hi, My brother is starting music college later this year and needs a laptop for making music (e.g Cubase). He can not afford the 15" rMBP so 13" of MBA or rMBP are the ones he's deciding between. If he gets the MBA he will get the 8GB RAM upgrade so the only difference is the retina screen and the better CPU. The screen doesn't matter that much for him. Is the CPU upgrade between Air and rPro enough to justify the expense or should he just go with the Air? And is an i7 upgrade worth it for music production?