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.
The crucial question is this one: "Java's static typing including seems to make it less prone to errors on a larger scale".  The crucial word here is "seems."  Sure, Java will help you catch this one particular type of error.  But how important is that, and what do you have to pay for it?  The overhead imposed by Java's type system means that you have to write more lines of code, which means reduced productivity.  I've used both and I have no doubt that I'm more productive in Python.  I have found that type-related bugs in Python are generally easy to find and fix.  Keep in mind that in a professional environment you're not going to ship code without testing it pretty carefully.  The bottom line for a programming environment is productivity - usable functionality per unit of effort, not the number of bugs you found and fixed during development.
My advice: if you have a working project written in Python, don't rewrite it unless you're certain there's a benefit.
Rewrite Python project to Java - worth it?