I'm not in grad school yet, but I have been using the surface pro 3 as my computer through my senior year of undergrad and I love it. I have the model with 8gb RAM with 256gb. I use programs like SPSS, Morphologika, and MicroScribe and have no problems with it being slow/ overheating. It does everything a regular computer does and its super portable. Even though it has a larger screen than the pro 2, if I stick it in my backpack with no books or anything, my backpack feels empty.
Its also been great for taking handwritten notes since it comes with a pen that doesn't lag. Another plus with the note-taking function is that you can record audio while you are taking notes. So if you look back at your notes, you can tap the pen on your handwriting and it will play back the audio from the point you wrote that note (a lot like a LiveScribe pen). Only thing I dislike is the keyboard track pad can be finicky sometimes, and the kickstand can be annoying if you are looking at your laptop laying down in bed.
If you are happy with your current laptop and you are just looking for a regular tablet to take with you class, go with the iPad; its cheaper than the surface. If you want something that can do everything your computer does and is super portable, go with the Pro 3. However, if I were you I might wait and see if Microsoft comes out with a surface pro 4 this fall because they seem to be releasing new ones annually.