As an owner of the original mini I do have to say the appeal of the mini is how comfortable is is to use casually. In bed reading things in iBooks is perfect on the mini. When I try to use it for textbooks though I just simply couldn't get into it. Nearly all my PDF's had to be zoomed then panned to see information adequately. And my textbooks were the same, I just want to be able to see the entire page on the screen without having to zoom/pan or anything. But with that said, I'm glad Apple does offer choice here and I hope your future mini 4 suits you well! As for me, with the help of users in this thread, I think I'm either going to try to get a good deal on an Air 2, or forgo until they update the 9.7 inch size. The cost is a big factor and the iPad pro would be likely overkill anyway. But I'll have my degree in spring 2017. So I'd like to get one sooner rather than later if I'm going to use it for textbooks.