I always laugh when I see posts trying to assert that performance is the gold standard by which to judge a phone or laptop.
I have a rMBP. They've taken a lot of stick, but it's the best laptop I've ever owned, and I bought it because, to my view, it's the best laptop on the market.
OS X Mountain Lion is a terrific operating system for a lot of reasons. I also use iOS devices because, while I think the OS has many shortcomings, it also has a lot of advantages over Android and Windows that matter to me, and these devices play so nicely with my computer and my data and my music system.
I find the Mac a wonderful machine to drive my stereo (though I do that with a dedicated headless Mac mini) and once you get used to a retina screen, it's hard to put up with the lower resolution devices out there.
For a student, however, I'd say it's damned heavy (though lighter than much of the competition). Have you thought about a MacBook Air. As of two years ago, I was biking to school through London four days a week, and I wouldn't have wanted to do that with this 15" beast. For the portability, the MBA is really a lovely machine, running OS X smoothly and, yes, there is also an optical out on that device. I believe there is an optical out on all Macs to be honest.
It's true that it doesn't offer the screen of the retina computer, but in real world terms (forget benchmarks) the subjective speed for the user is blazing. When Jobs stood up and said that he believed the Air represented the future of computing, while the first and even second generation machines weren't quite there yet, today's MBAs are fantastic devices.
And so is my rMBP
Hope that helps
The problem with the Air is that it does not have 8 gigs of RAM or an optical out. I like the form factor though.