To add to this: any time somebody at my company who doesn't work on our Python services every day has to dip into them for a one-off task, it takes a day or two of troubleshooting their environment just to get to where they can start working with the actual code. And this isn't necessarily from scratch: any Python environment that's sat still for more than a few weeks becomes inevitably broken. It's a huge time-sink and I have to think it offsets any other productivity gains that Python may be giving us.

Personally I refuse to touch our Python services with a ten-foot pole. My local app hits the testing environment and that's that.