moving the Rocker Apex point?

Has anyone here ever tried to move the rocker apex point? most boards have it dead center pretty much but ive seen a few that had the apex point moved back, Chas shortboards come to mind and ive seen an Aussie board (Pipedreams? i think)like this with the apex moved back to just in front of the fins. If you have tried it how does it ride compared to a more conventional rocker?

In very broad terms, moving the apex up creates more drive and is better in most flat faced waves. Moving the apex back makes the board looser and is better for hollower waves.

How can you tell where the apex is, It’s tough to measure.