You got me a bit confused here. If I understand correctly what you 're saying, you 're still using Python for prototyping the core algorithms and C++ in actual production systems. I'm not saying Python is not good for production systems in general, I'm wondering whether it is good enough for real-world implementations of machine learning algorithms.
Also, I believe most people would consider Java as an alternative to C++, hence all the Java-based Apache projects, such as Mahout, Solr etc.