Harper really did knock it out of the park - I came away with a file full of notes and a desire to implement the same practices with my Drupal Commerce team.
Some great quotes from the session:
"Think about building a billion dollar enterprise from zero in eighteen months." (Queue the stress.)
"The OFA framework is a framework I call 'Use all the things!' We focused on what simply solved our problems."
"Groundhog Day is all about multivariate testing." : )