What I can tell you is that we thought about in the same way as bringing on a co-founder or superstar employee. The value of YC isn't measured in their investment, but rather the value they bring.
Even in terms of the boost to our valuation alone from the validation, beyond everything else, YC more than paid for itself. If you look at our growth graph there's also a sharp inflection that starts shortly after we joined the program. That could be unrelated, but it's my strong belief that it was the value of the program that helped us accelerate.