For backend/webservices, I initially tended to agree Go is a killer tool. But if you are a Python shop, why would I bring this into my stack instead of using PyPy (or soon, Pyston) for CPU-intensive tasks? I say this as someone who has never really ran into issues with Python performance, but am looking towards learning Rust once it hits 1.0 for writing my first non-Python library because if I can find something CPU intensive enough, I can justify deep diving on Rust.
Doesn't mean I won't ever run into performance issues, but even Rust may not be necessary (for me), with PyPy/Pyston around. Go itself is more a replacement for other tech, rather than complimentary, which in my view is the biggest drawback not on your list. I like things with big ecosystems that work well together so you're not stuck on an island, and the Python/C(++)/Rust world has great interop. Unless you're a true Go diehard about the language for whatever reasons, this isn't really what I think many like myself are looking for. I see more value in simply adopting another implementation of a shop's existing platform, if you have so many options at least.
I'll be really interested to hear responses to this, as I don't feel interop with Go has been discussed often. Seems people who really like Go are either 'all in' or not at all, figuratively and literally.