Do you think that was the right choice, or would you have written that in Rust if you were starting today?

Go is great for backend stuff like that. If we rewrote it from scratch today we might consider Rust though just to have only one language in the house... but Go is really good for that case.

We are using Rust for the ZeroTier network hypervisor and core system service though because that's systems-level software that is performance-critical, needs to fit on small-ish devices, and needs deterministic performance among other things.

They're really different languages for different niches. Rust is C++ 2.0. Go is fast compiled Python with a cleaner design. (Python is the best niche comparison I've found for Go.)

Very interesting! Thanks for the answers! :)