[crazygringo]

Exactly.

With academic articles, I virtually never want to simply read them online.

I need to save them for future reference, read them later when I've set aside time, annotate them, refer back to my annotations four months later...

Arxiv (or JSTOR or wherever else) is just where you get the papers. It's not where most academics are going to be consuming them.

(For consumption, a full-size tablet like an iPad, with a stylus or Apple Pencil, is absolutely ideal.)

[jpindar]

Same with electronic part datasheets. I need to be able to mark up and save datasheets along with the other documents which make up the design of a product.

[ImaCake]

Can I ask what app you use on your iPad for reading PDFs? I use Adobe reader which is pretty good on iOS, but I find Preview a better experience.

[sjy]

I have been maintaining a PDF library this way using GoodReader for about 10 years now. You can connect it to most cloud storage services or any SFTP or WebDAV server, and sync annotations with Acrobat, Preview, Okular, etc. on the desktop. I have still yet to find something this good for HTML or EPUB documents.