These sound more than a little reminiscent of Enve's 4.5 ARs. In the profile including 25 mm internal, in being extra fat, and in being hookless. These are about 150g lighter which at that kind of $$$ is nothing to sneeze at. I'd rather have the Enves any day of the week and twice on Sunday, but it's an interesting development and if I was going to buy Zipps it would be some flavor of 303s.
The Enve wheels were made for the cobble races, and are marketed for mixed surface rides where you want control on the gravel and speed on the pavement. I don't know the story behind the Zipps but they'd excel at the same kind of riding.
I've beaten the crap out of mine, and I'm built like a football player. Really amazed at the abuse they stand up to.