While both are clearly important, if we only have so many hours in the day I'd rather a high school student have a grasp on basic stats than basic formal proofs.

As a data point of one (heh there's that stats again...) my two high school geometry classes 15 years ago never touched any proofs. I have no clue if they still teach that way.

Edit: just noticed that I'm replying to someone who is far more knowledgeable about math than me. I stand by my point though, people like Colin can seek that out in more advanced classes.