Am sure they will be fine, they have same design on GTR's that are doing track work, all Wortec focus on primarily is brake disc design and innovating on how to reduce weight and improve cooling, quite a lot of other cars running their thermal slot design and all seems well, I won't be racing my car or doing a lot of track days and the disc have a warranty with them so should there be an issue I am sure they will resolve it.
I was originally going to go with just plain edge and plain drilled, traditional style as I believed the suncut would look smaller and the grooves would make too much noise. But once on the car I fell for the look for of them and though the grooves create additional braking noise, its only when braking hard from high speeds, so kept this design.
Plus at Santa pod the attention the car got and a lot of comments on how cool the brakes looked, its a unique design and certainly got a lot of good comments, the car had crowds of people around it at times.