It seems like the academic publishing model would be useful here (and in fact that might be what they are doing with alums reading applications.) Each paper gets a few reviewers, which quickly determines the definite accepts and rejects, and the whole committee need only discuss the ones in the middle. The way partners and alums are structured in YC, it would probably be ideal to weigh reviews accordingly.

There will definitely be some noise, but one would hope things will shake out as they should most of the time. At least that's what I am hoping.