On Mac, when editing a Mask with the Pen tool:

press Command when over a point to get the Delete Vertex tool

press Option when over a point to get the Convert Vertex tool  (you may need to use Command-Option officially as Mac uses the Option key )

and just click anywhere along a mask outline to get the Add Vertex tool

By using these shortcuts and using the default Preference (toggle is ON), you can then use G exclusively for switching quickly between the vertex editing and Mask Feather editing.