If you don't like LOC, then what sort of interpretation are you giving to "100x more productive"? I'm not so sure LOC is way off.
But in any case, if a person says he is "100x more productive" in one language than another, then I expect he can complete in 1 to 7 days what would take 100 to 700 days (i.e., 3 months to 2 years) in the other language.
Strange that I have to even highlight the obvious, but anyone who says they're 100x more productive in Go than Python is exaggerating to an extent that I find it hard to trust anything they say.
Again, "lines of code" is a shitty metric. Functionality might be one, customer support might be another... but even if you choose LOC, 100x is not impossible or even unlikely. When learning Go, I went back to undergraduate coursework, and picked some example problems from an advanced programming class. I solved these problems with Go.
Seventeen years ago, I dropped that class, because it was taught in Java. According to pure LOC, I'm something like 10,000,000 times more productive in Go than in Java, because Java was so gross I chose to withdraw from the course rather than waste my time rolling in mud.
Perhaps, setting LOC aside, a given programming languages matches a developer's thought habits better. In such circumstances, not only does she finish the nominal task quicker, she is able to respond more quickly to QA feedback, or to changing requirements, or to other business considerations. Perhaps a different paradigm enables her to foresee shortcomings in an existing design. These things not only improve one developer's productivity; they make the entire team more productive.
There is so much more to programming than "how many lines of text did you shit out today" and it is incredibly naive to behave as though LOC is the prime metric. We, as an industry, have been aware of this for at least forty years now. It's time to stop.
It's difficult to write a program without writing lines of code.
There are dumb measure, smart measures, and dumb ways of applying smart measures. We could consider a little intellectual generosity, that intentions were well-met, and not that a 50 year old used car salesperson turned programing manager was irrationally demanding X lines of code per day.
But in any case, if a person says he is "100x more productive" in one language than another, then I expect he can complete in 1 to 7 days what would take 100 to 700 days (i.e., 3 months to 2 years) in the other language.
Strange that I have to even highlight the obvious, but anyone who says they're 100x more productive in Go than Python is exaggerating to an extent that I find it hard to trust anything they say.