Where do you use Go?
Backend to my.zerotier.com and internal analytics code.
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.)
Rust async code can be a bit challenging until you get it, but I can't think of a way to make it that much simpler without sacrificing the whole "systems programming language" concept or support for embedded. The only good alternative is Go-like fibers and that requires a fat runtime.
We use both Rust and Go at ZeroTier and find that they both have their own niches. (We are slowly moving ZeroTier from C++ to Rust to use a more modern and more importantly safe language.)