[Rowern]

My company has 2 big projects running on HHVM.

Most of the library we used to start our projects (symfony, mongodb to name the biggest) dropped the HHVM compatibility in the middle of development, I can tell you this was a good lesson for me: never take a technology where big vendors drop compatibility.

Having to debug a production error with an HHVM library (which support was dropped), find a fix and then seing it was fixed in the official PHP library 6 months ago hurt a lot...

Another point not in favor of HHVM, it's maintained by them, the roadmap is only known to them and the number of HHVM alternatives to big libraries is near 0.

We are gradually moving away from HHVM (and PHP in general) in favor of NodeJS and TypeScript.