About a year ago (July 2015) we ran a webinar with Rick Still from the FT about their journey to move their new site to full HTTPS delivery. Once that had been done they turned on h2 delivery and had some early indicators of performance improvements.
One year down the line I am speaking to more and more customers where making the move to HTTPS is only just happening. The carrot for a lot of this is the performance gains on offer by h2, the additional features of server push that are getting more attention and other features such as Service workers, Geo location services and improved SEO rankings.
This video shares some insight from the FT about moving to HTTPS.