Often I will do some prototyping with scikit-learn and then write my own implementation in numpy / scipy for something that goes into production. But I have used scikit-learn in production as well without issue. I have used MATLAB a bit and it is quite nice for figuring things out / prototyping. But the issue I have with it is that it's not typically intended for production software. So then you often need to reimplement your MATLAB code in whatever "platform" language you're using. That's why I've largely transitioned away from MATLAB.