If should be obvious that GaN does not guarantee better performance.
No, but if the GaN semiconductors have been implemented right, it is the one to use today
And with this Class D Audio USA made one, it could be just a ready made board from GaN to use, in whatever case one see fit, like a $20k one could be using the same board. As Class D Audio did use Ice Power & Hypex boards for some of their kits in the past.
https://gansystems.com/evaluation-boards/gs-evb-aud-xxx1-gs/ These specs are very similar to the Class D Audio USA made one
Cheers George