Currently the owner of an iPhone 6+ and iPad 3. Entering medical school and have a large library of 1000+ page textbooks in PDF and ePub form that can be up to 350MB. My favorite PDF annotation software right now is PDF Expert 5 but it is very slow on the iPad and crashes constantly on the iPhone when I have any document greater than 50MB. Good reader is faster with less crashes but lacks continuous vertical scrolling and is not as smooth at annotating/highlighting IMO. Will an upgrade to an iPad Air 2 or 9.7" iPP be a worthwhile investment if this is my primary use for the iPad? Will I see a noticeable difference in PDF Expert? Ideally I would go to the Apple Store and load PDF Expert with one of my large PDFs onto their models and see the difference but I doubt they would let me. Any opinions are appreciated. Thanks!