> the side effects of making your team less productive by using Rust is a much higher price to pay than just running you Go service on more powerful hardware.
This entirely depends on the ratio of development effort to deployed instances. At one end of the spectrum, lots of developers work for years on a system which is only deployed on one machine; obviously you optimize for developer effort and buy a single massive machine. At the other end of the spectrum, a few developers work for a short time on a system which is deployed at massive scale; obviously you optimize for performance.
At Pernosco we have a very small team deploying a relatively small number of instances, and after five years of Rust we're very happy.
My problem with Rust: I'm sure that if I used it as my primary language for a couple of years, I would be able to claw the productivity loss back. But I can't find any reason to justify using it at my current productivity level.
There is a vicious cycle: few projects use Rust because the productivity hit is large, and programmers do not get enough experience using Rust because few projects use it.
I don't think that 5 years is needed to feel productive. I started Rust a few years ago, but I dropped it due to lack of time and I remember that I had a really hard time with some of the stuff (most notably futures between async/await). I got back in 2019 and I wrote maybe two small projects (under 300 lines of code each I think) and I read quite a lot. After that I got to implement a production web service and also mentor/teach two people. It went very smoothly and for the most part there were no major blockers.
Obviously it all depends on a lot of stuff, but I think that for most people a few weeks to month of writing Rust at work (meaning full time, not like an hour in the evening here or there) should be enough to feel decently productive.
Another thing is that if you've tried Rust long time ago check it out again. I think that both the language and the ecosystem changed a lot in the recent years, it's hard to compare how easy it is to do Rust now vs 2016 or 2017 when I first tried it.
I don't think that vicious cycle exists. I was immediately productive with Rust, but OK, that's just an anecdote. Surveys such as Stackoverflow's Developer Survey show Rust usage growing rapidly.
If I met someone who took years to be productive with Rust, I would conclude they lack aptitude for programming. Maybe harsh, but probably true.
This entirely depends on the ratio of development effort to deployed instances. At one end of the spectrum, lots of developers work for years on a system which is only deployed on one machine; obviously you optimize for developer effort and buy a single massive machine. At the other end of the spectrum, a few developers work for a short time on a system which is deployed at massive scale; obviously you optimize for performance.
At Pernosco we have a very small team deploying a relatively small number of instances, and after five years of Rust we're very happy.