After many years of putting up with the nagging inconvenience, I finally was able to put the time into wrapping up the conversion of our character rigging scripts from MEL to PyMEL. This is a pretty nice feeling:
No more switching between languages, text editors and syntax.
No more pm.mel.eval() in PyMEL and python() in MEL.
The ability to use classes/objects.
The code is much more concise and easy to read.
There are great IDEs to work in for Python and now I can stick in them.
The ability to use PyNodes.
The old code is refactored; I have learned a lot in the years since some of this was written.