It would be interesting to see some data, some A/B test of these ideas. Let's take some projects of various complexity - some personal webpage, online calendar

It would be interesting to see some data, some A/B test of these ideas. Let's take some projects of various complexity - some personal webpage, online calendar, social app, etc. And lets do these in Vanilla CSS - just some clean proper style.css in the <HEAD> and exactly the same project with all the inline styles with some JSS etc. And let's discuss then. At what point in project's complexity what makes more sense. Which code is more readable/maintainable/etc. Performance gains and etc.