Q: Are these worth it for a car that mostly sees track days?

For track use they open up real tuning freedom. Rear toe strongly affects corner entry stability and how the car rotates, and the fixed factory arm gives you none of that latitude. With these you can set a small amount of toe-in for a planted rear or experiment for sharper turn-in. UP built these for greater freedom in alignment settings and better on-track behavior, the kind of edge that pays off during a TeslaCorsa Track Day Experience.