It seems that the majority of the benefit was replacing a browser instance (PhantomJS launched via Karma) with a virtual-DOM (jsdom).
Karma shines when you're running integration/e2e tests against _real_ browsers, especially IE.
Karma shines when you're running integration/e2e tests against _real_ browsers, especially IE.
Using Karma and Phantom for unit-testing it's just overhead to me.
If you want to run automated tests on every browser, you pick up a SauceLabs account, configure the simple zuul.yml file, and you're done. If you wanna run it locally, you run the zuul cli tool and open the link with that browser.