My experience with Ruby and RoR is fairly limited, and I have no experience with unit testing (very embarrassing). I'm not sure I'd be a good fit for Shopify. :(
That said, I've recently had a dire need for concurrency on a personal project and Go fits the role very perfectly. It's also a very "clean" language to work with, and I distinctly get the impression that doing things "the Go way" leaves very little opportunity to do "dirty" things.
The Go language designers did a very nice job at creating something quite robust without making it excessively verbose.
