Actually, Duo would most likely be integrated into Gulp or Grunt.
It's more analogous to the existing workflow of using NPM to download packages from registry.npmjs.org and browserify to bundle them together.
Only we're using Duo to download from Github and bundle them together.
Well for one you won't need to specify the modules you need with more than the require('somemodule') statements in your code.
And it can grab modules/components/files directly from github which can be a plus if you have some private modules you use.
Hmm that's kind of what I'm gathering from it. It looks like instead of creating a grunt or gulp file to manage your assets, you write that directly in... a different JS file?