Hi Peter, is it possible to make the IMac mouse up/down gesture operate the zoom when the cursor is within the waveform area and when you move outside it, it reverts back to normal scroll of page up/down, this would speed things up greatly.
So then you have the left/right swipe to move within the waveform and once you find your point of interest you simply swipe up/Down to zoom , I would also have both of these gestures ignore the follow playhead no matter what selection state you are in as priotity is creating loops not following a playhead.