I've tried switching to Atom several times, but performance always brings me back: Sublime can edit a several-megabyte file with no stress, Atom becomes unusable; I can bash keys in Sublime and they instantly appear on the screen, there's an almost-noticeable-but-wait-is-it-even-really-there-yes-I-think-it-is delay on Atom. Also, vim mode isn't as robust as vintage mode (`ci"` to change the stuff inside of quotes, in particular, doesn't work in Atom).

I really hope whatever javascript/html/css framework they've set up has a lot of room for performance improvements. I'd much rather be using something open source based on these technologies (which, for me at least, would make the editor much more hackable).

As far as I could tell, Atom didn't have per-syntax settings. That made it a non-starter for me.