Don't dismiss the value of Git integration in your editor until you've tried Magit in Emacs. I hardly ever need to run git at the command line anymore. I particularly like how easy it is to stage individual hunks in Magit.
Magit is probably my favorite piece of software. It's truly epic. It alone would keep me from ever switching to something else. Although emacs has plenty of other things to keep me around.
Also check out http://porkrind.org/commit-patch (with commit-patch-buffer.el) for an alternative to magit's hunk staging which is also works with a bunch of other VCSs (it's heavenly when you're stuck with something old like CVS or SVN).
Now you've got me interested, wonder how something improves "git add -p". Will check it out.