Is this practical question or an attempt to find an excuse to not use Rust?
Guaranteed copy elision is an interesting property, but it's C++17 property which means most C++ codebases don't use it.
Similarly the ability to create object on heap without unsafe code is something that is nice in theory but quite problematic in practice. But we may hope that in year 2034, when Rust would be as old as C++17, that would be a solved problem. We are not there yet, though.