> It probably also helps that extending Atom is much more approachable given that it's all Javascript...
I've heard this said before, I've had the opposite experience. ST offers a small api and it was easy for me to make something work with a single .py file. I gave up trying the same thing in Atom; the api is larger and lower-level. Admission: I don't know coffeescript.
ST of course isn't nearly as flexible, there are many things you just can't do.