I'd have to agree with these folks. The only thing you will lose, that is worth mentioning, is the ability to run two drives. To me, that's more of an upgrade on an older machine, more than anything else though. The bad side to NOT getting a retina, is losing thunderbolt 2 and USB 3.0.
If I were in the market for a Macbook NOW, I would wait till the newer model comes out. If you NEED one NOW, buy used. For studies, even a mid 2010 model would be fine. Mine runs "high end" software but is limited to things that have come out within the last year. If you can hold off for a few months, I really think buying a used, for around 3-5 hundred is the smart thing to do. Then, when the newer ones come out, and if you've taken care of a used one, you can get almost all of your money back on resell, depending on what you get.
Between my mid 2010 and my late 2014, I'm confident you'd do fine with a used, until you can see what new features may be on the ones that haven't come out yet. I'm gonna kick myself in the ass if the new ones have USB type C, seeing as though I bought my new one in November and specked it out (13"). So resell isn't going to be that great because nobody is going to want to pay close to what I did, for the sake of 1tb PCIE. I'm a musician who needs to work on the go at times, so 1tb was a must. The libraries and plugins I use the most, take up over 500gb and it was worth it to not have to worry about carrying a drive around.
That's my opinion though. It all comes down to what you NEED and WHEN.
