Which one? (Be helpful if you had pros and cons with your answer)

[Cynette]

I don't quite understand if you can only do one or the other, because I cannot visualize your description of the second concept.

But for the first one, this sounds feasible to use for herding. Just a couple of considerations: Make sure that the "arms" are strong enough to take a ball dropping / bouncing on them from the hurdle height. Make sure you plan on a way to ensure that you can release the ball as you cross your finish line or you won't get the points for herding the ball. And make sure you keep the the robot with its arms extended within the 80" imaginary cylinder.

Good luck!