PyPy has LOTS of problems with 3rd party libraries. If you want to deploy it in production you'll have to check that each one of them does exactly what you need it to and oftentimes you are surprised how things are broken.

We are using PyPy for some of our services (where it is doing about x3 faster than CPython), while for some others (Django UI - at least the way we are using it) we found that PyPy is actually slower, so we are sticking with CPython.

Unfortunately PyPy team has not even made it their priority to test PyPy with Django. It is one thing to have a cookie-cutter test suite that measures simple use cases and it is entirely different matter to test how well it can run the whole stack of apps on top of it.