The best M↓ editor I've used is Haroo Pad[1]. I like it because you don't need to visit a webpage to use it which makes it ideal for offline idea dumps while you're on a plane for example.
I'm gonna look into your setup though. I'm definitely all about being on the terminal, does your setup work well with VIM as well?
Congrats to the creator of StackEdit, it seems very well done. It also seems to work really well while offline, which is nice. The biggest blocker for me is that when I need to create or edit a markdown file, it's usually a local file in a git repo. In my case, it is simply more convenient to use a native app.