2,000 characters is not so much.
I sometimes export notes to Evernote, if I really really like the quote. More often, I make notes and highlights because I'm a reviewer and I will save something to jar my memory during the reviewing process. In those cases, the annotation doesn't live after my immediate need is gone.
Usually a review note is something either very good or (more often) very bad. Evernote notes are things like "huh, that made me see something differently, and I want to save that".
I use a 32GB SD card with the reader. I REALLY want a 350, but I cannot live without an SD card slot.