Is Mythical Man-Month still relevant in todays AI Vibe Coding world?

Yes. Maybe more so. The most famous lesson from that book is that you can’t just add bodies to a team and expect proportionate increases in productivity. I think vibe coding means more people simply makes the unmaintainability increase proportionate to the number of added people.

Has anyone worked on a project with the "Surgical Team" organization? If so, how well did it work compared to other team organizations?

I think the idea had a lot of merit, but have never seen it in practice.

It is. So much so that I quoted him and even included a photo in my latest article[0] about AI pair programming.

[0] https://levelup.gitconnected.com/you-are-bugs-improving-your...

Even more so, it’s harder for two vibe coders to work in a single repo where AI is making repo wide changes.