Of those two, I think Tumbili definitely looks like the better choice for me. Arashi looks absolutely nauseating. But if you can tolerate it, well then the choice is obvious.This pov should help clear things up- but watch the track. You’ll see the fins.
Tumbili POV
And this freespin is in Japan- but this video focuses a lot on the flipping mechanism. You can see the flipping getting activated with the fins. This one is called Arashi, over at Nagashima Spa Land.
Arashi Nagashima Spa Land