Earlier quoted context omitted.
The OS isn't better at it if there is none or limited ability to manipulate the windows in a keyboard driven way. I use and love the 3rd party tool SizeUp, but SublimeText2's integrated pane management (including moving tabs between them) is far better than plain windows.
Can you help me understand how it's better? SizeUp looks perfect for something like this. Want to view two files? Ctrl-right on one, it's now on the right side of the screen. Command-O, chose the new file, Ctrl-left on it, it's now on the left side. I'm honestly very curious what Sublime/etc offer that is better than what you can do with the OS?
Granted, I only know that from using VIM (and occasionally SublimeText), but it's been one of my "Dear GOD Give Me This in TM" requests for a while. I've got SizeUp and love it - truly one of my must-have apps - but to me it's a hack, not a solution.