I use my iPad Mini 3 for reading PDFs such as data sheets, schematics of circuits, photography books, and so forth. I can understand your interest in larger sc

I use my iPad Mini 3 for reading PDFs such as data sheets, schematics of circuits, photography books, and so forth. I can understand your interest in larger screens such as the iPad Air 2, but there are so few book I even have access to (much less, use) that are that kind of format. The largest books I regularly use are O'Reilly publications. My notes are usually taken in A5 spiralbound notebooks, or Field Guides pocket books. A4 is a gigantic format for me. As for ownership of books, I buy DRM where possible, and strip the DRM from the books which aren't available any other way. So I have Michael C Feathers, "Working Effectively with Legacy Code" in my iBooks library even though it is exclusively a Kindle book. Yes, I had to taint my credit card with the stench of Amazon, but I won't let them take back something they have already sold me. Especially when the electronic version costs more than the paper one!