It probably depends greatly on what you are doing. There is a lot of work where I would be much more productive in Go because I have yet to really master Rust, as it is a big and complex language while Go is so simple. But I have also made a library where the various meta-programming features in Rust saved me thousands of hours of work and ongoing maintenance compared to what it would have taken to recreate it in Go.
Similarly, the productivity difference will depend on how much run-time performance you need. It might be take longer to make Go code very fast if you need very fast. Having to work around the garbage collector, and avoiding interface {} etc.
Similarly, the productivity difference will depend on how much run-time performance you need. It might be take longer to make Go code very fast if you need very fast. Having to work around the garbage collector, and avoiding interface {} etc.