Having read this, I decided to try it out today on our jolly. I watched what I did (IYSWIM). It's both, but with a tendency to use specific settings for specific purposes - so 17 inches, 2300RPM for a "normal" approach, then pitch to control both speed and sink.
That works up to a point, then power has to be added or subtracted for coarser corections. There are a lot more pitch changes than power changes on a typical Keef approach.
Not sure what that proves - but I did like the John Farley article and his way to show the bemedalled CFI his point!