Go check the pictures..
At the European Championships Koen Naert who won and is a New Balance athlete took a New Balance 1400 upper and put it on the sole of a vaporfly 4%...
The Spanish guy who finished 6th and is also a New Balance athlete took a vaporfly 4% and just rebranded the whole shoe with New Balance logos and different colors....
So there you have it....... Athletes from other brands who are sponsored even believe in the vaporfly 4%