Interesting, I never came across this one in my search. I'm gonna give it a try, I'm curious to see how it compares.

I did try out a couple other editors that leaned on markdown though with mixed results.

One thing that stands out to me in particular with iA is the way they've implemented (at least based on the homepage video) note linking. That click-through implementation forces you to leave your document, which is something we explicitly didn't want, since typically what you're doing is scanning through your notes and your document simultaneously while you work out how everything fits together.