Yes, I would say it is quite stable. In fact, in the ST blog it says: "Sublime Text 3, while still technically in beta, is the recommended version of Sublime Text to use." [0]
I use the dev version (currently on the latest build 3092) for all of my editing, never had an issue. And if it should ever break, it's easy to download the next-older build and use that. Very satisfied.
I don't have issues with large files on OS X.