2015 Programming Languages?

[Monochron]

I wouldn't imagine the new control system would prompt teams to switch, unless something comes out indicating an issue with one of the main three languages.

Our team did Python the first two years and are now switching to Java mainly for ease of use and the ability to compile in a nice IDE. Disclaimer, I didn't actually work on programming this past year, I'm just relaying what I remember hearing from them. So take this with a grain of salt.

We ran into a lot of annoying syntax errors that would have been caught instantly by Eclipse and would have prevented us from loading obviously bad code onto the robot. We also had issues with the routing tables at competition. I'm not sure of the exact issue, just that our programmers firmly believed that debugging the issue would have been straight forward in one of the main three languages, but in Python it was challenging. Also, the community for using Python in FRC is much smaller than the big three and it can much more difficult to get help on weird issues. That isn't a huge limiting factor though, because the MPI interface for Python is very similar to the C++.
Again, this isn't first hand knowledge, but I recommend you look into other teams' experiences before committing to the switch.