tl;dr: Use New Relic and use Unicorn. Weren't these two things that the RapGenius post specifically mentioned as problematic? (Cost and memory constraints, respectively, IIRC.)
As for unicorn, unless your application is a real memory hog it should be possible to run 2 workers, which is a big improvement over using thin. But this is now the standard advice being given by Heroku, so there's not much new here.