Is there any benefit in using the Touchpad or Analog Sticks for the Sliders?

Solution 1:

Using the sticks/touchpad would be more similar to the arcade version of Future Tone (which I think came first). The arcade cabinet controls consist of the four buttons in a row and a slider bar on top. You swipe the slider bar for the arrows. So if you want to replicate that playstyle, you would want to use the sticks or touchpad.