TipTap Up/Down instead of Left/Right?

I (and probably others) would have a use for a TipTap Up/Down gesture. It would function the same as TipTap Left/Right, except you just press your free finger below or above your fixed finger on the touchpad.

I specifically would like to use it for navigating vertical tabs in my web browser. Since the tabs are vertical, I think TipTap up/down would feel more natural.