It entirely depends on what you mean by "the product" and I can't help but feel that you are deliberately missing my point. Suppose we take it as a given that

It entirely depends on what you mean by "the product" and I can't help but feel that you are deliberately missing my point. Suppose we take it as a given that for any given program, ignoring performance, a pure Python program requires fewer developers to implement the same number of features than the same program in C++; does it then follow that we would need fewer Python developers to build a web browser than C++ developers? It does not, because you simply could not build a web browser in pure Python that would fulfill people's performance expectations. But for many other projects, the claim does follow, because they are within the realm of "stuff you can do in pure Python." My claim is that a similar phenomenon applies for C++ and security, regardless of whether Rust is otherwise more productive: no matter how many people you add to a large C++ project, you are not going to come close to the level of assurance on security properties that you get from a Rust program of the same size (your only real hope is formal verification, which for verifying code in just about any language is multiple times less productive than writing the same code without verification). For these cases, asking which is more productive is pointless--C++ cannot deliver the expected product. However, if this is not the case for your project, I believe Rust's productivity benefits are more modest and are probably outweighed by things like team experience and available tooling. I think I'm being pretty clear here about what I mean and why your question does have a single answer that applies in all situations.