[pjmorris]

I realize these aren't controlled experiments, but consider two sources:

1) Alistair Cockburn has a communication chart [0] suggesting that face-to-face at a whiteboard is the most effective form of communication. He's been showing the chart for at least a decade, to rooms full of engineers from all the big players and lots of little players. If he were wrong, he'd eventually run out of consulting clients, but that hasn't happened. I realize this is a weak argument.

2) YCombinator co-locates its funded teams. I'd wager they're familiar with the arguments for and against remote work, that they're technology savvy, that they're data-driven, and they're incentivized to get the most for their money. I realize that this second argument is the same as my first, but I think these arguments should make you think about why they put a premium on in-person collaboration.

[0] http://www.agilemodeling.com/essays/communication.htm