All good points, except the last...
Does anybody use PyPy, Jython or IronPython for a production web service? I'm seriously wondering.
I've had the misfortune of having had to use Jython, but just to read Python pickles from a Java service (don't ask). Even that simple use case wasn't fun (the last stable release was also over a year ago).
PyPy looks great for small or new projects, but there is this disclaimer: "PyPy has alpha/beta-level support for the CPython C API, however, as of 2.1 release this feature is not yet complete. Many libraries will require a bit of effort to work..." - this has caused PyPy to be incompatible with every large Python project I've ever worked on.
And well, personal (dis)taste in .NET aside, IronPython hasn't had a release in over a year either...
Where are these projects being used in production?