When did you try it last? We spun up a whole team (which I'm on) who's entire goal is to make all of the world's PHP code runable on HHVM. All of the top 20 PHP frameworks work on HHVM now.
I use HHVM in prod. I love it, well done :) I'm actually putting together an app dev "template" for composer to be used with HHVM, and a few compo sable libraries. Not a framework, but good libs and best practices.
http://www.hhvm.com/blog/1499/locking-down-for-performance-a...