> that experienced developers' performance suffered when using an LLM

That experiment is really non significant. A bunch of OSS devs without much training in the tools used them for very little time and found it to be a net negative.

> That experiment is really non significant

That's been anecdotally my experience as well, I have found juniors benefitted the most so far in professional settings with lots of time spent on learning the tools. Senior devs either negatively suffered or didn't experience an improvement. The only study so far also corroborates that anecdotal experience.

We can wait for other studies that are more relevant and with larger sample sizes, but till the only folks actually trying to measure productivity experienced a negative effect so I am more inclined to believe it until other studies come along.