I don't understand how you switch from “wow, guy wrote a language I can use in my projects” to “why should I switch from PHP, I need a more compelling reason” and stuff.
And yeah, PHP sucks. And your career path is something you should not think about at all.
There are 11 versions of Sinatra’s README which don’t share any general templates. They should be manually edited after each release. This is kind of thing that needs automatization.
Plus, it is much easier to inject badges by a mixin, not by copypasting and manually changing some elements from your old READMEs.
Hey, I am the Sword author. Harp development and Sword development have begun almost simultaneously. You should stick with Harp if you use typical NodeJS tools for templating (like Handlebars and Stylus), and use Sword if you prefer Ruby ones.