The study itself from late 2025 is also written to be _highly_ favorable to non-ai usage. Developers on a codebase they're already experienced with, largely using these tools for the first time. Of course they aren't faster! They've already done the hard part! They're also open-source maintainers, which, ime, means they're already a cut above the average dev.

I'd be much more curious on a study that used regular developers on brand new-to-them codebases for significant features or migrations. I'm personally encountering what I'd describe as a 200%+ productivity boost.