I think the best way to characterize Rust ’s productivity, is to put it on a quality axis.
If you want low quality code (prototyping, etc) rust is much less productive than the alternative.
For medium level of quality, Rust is similar to others.
For high quality code, Rust is much more productive than any alternatives.
Quality is intentionally vague, to encapsulate performance, leanness, documentation, and security.