I would prefer to have the brush outline disabled while inking but enabled while painting. To speed this process up, I've added an action that will either disable the brush outline, or enable the brush outline using the last set outline shape.
I don't think it's necessary to have separate actions for each brush outline option as I would assume the preference between the three shapes is set-and-forget.
This is not necessarily related to !1426 (merged) as this action wouldn't touch the eraser cursor.
Use the action as a shortcut or toolbar action. Make sure the user-preferred outline shape is properly read and written.