First of all, I love Python, and I currently use it for most stuff. However, as a PhD student, I mostly implement prototypes for testing and evaluating ideas. This also includes that I'm usually the only one coding, and that -- while I certainly try to write half-way efficient code -- performance is not a primary issue. And for quick prototyping, Python is for me just neat. 
Now I consider to go with some of my stuff more "serious", i.e., to bring it into a productive environment, make it better maintainable, and maybe more efficient. So I wonder if it's worthy to rewrite my code to, say, Java (with which I'm also reasonably familiar). I know that Python is not slow, but things like Java's static typing including seems to make it less prone to errors on a larger scale, particularly when different people work on the same project.
It's only worth it if it solves a real problem, note, that problem could be 

I want to learn something better
I need it to go faster to reduce power requirements in my colo.
I need to hire more people and the talent pool for [insert language here]
is too small.
Insert innumerable real problems here.

Python and Java are both suitable for production. Write it in whatever makes it easiest to solve the problems you and or your team are facing and if you want to preempt some problems make sure you've done your homework. Plenty of projects have died because they chose C/C++ believing performance was going to be a major factor without thinking about the extra effort involved in using these language well. 
You mentioned maintainability. You're likely to require more code to rewrite it in Java and there's a direct correlation between Bugs and LOC. It's up for debate which one is easier to maintain. I'm sure both camps believe theirs is.
Of the two which one do you enjoy coding with the most?
Rewrite Python project to Java - worth it?