The information in this thread is correct. I'll add this statement from the RobotPy FAQ:
"...we’ve found that most problems teams run into are problems with WPILib itself, and not RobotPy."
RobotPy and RobotDotNet implement the same WPILib interface that the official languages use. Often, the problems people run into at competitions tend to be in figuring out the right logic to accomplish a task, as opposed to actual bugs with the language itself -- and any team can help you with that, regardless of language.
RobotPy has had good off-robot testing and simulation support for many years, whereas the official libraries are still not completely there yet.
