Has anyone else actually played with the CP FTP calculator mentioned?

You put in 3min and 12min power.

Critical Power Calculator | Two Wheel Blogs

Based on power curve of some recent segments, I get 306 watts FTP estimate.

Doing the same with two of the points from the curve that Dunbar provided gives 279. So maybe the calculator is in question.

Some of you with established FTP should give it a try and let us know if it's reasonably close.