Welcome... and stop pouring, you'll get the squirrels wet. I too went through much angst, and when I finally decided on a device, guess what? It doesn't matter, because in the end I'm reading books. As someone here recently said (I can't recall who, sorry, or I'd give proper credit) "
the device disappears".
I guess I'm giving this caution: do your research, check out book sources for the various devices, make a decision on this PDF thing, but don't do SO much research and dithering that you build up unrealistic expectations of what these things do. It's all about the books, baby.