The big question proponents of Universal Basic Income must answer is: does direct stimulus of aggregate demand result in real growth? Is risk de-incentivized when a labor market participant is not required to work for marginal increases in "happiness"?
Taking our current central bankers experiments with quantitative easing (and now, perhaps, quantitative tightening) as a proxy for injecting liquidity into the system I think there is at least one evident result: bubbles forming in even the unlikeliest of places.
In any case, full support for YC's experiment and can't wait to see the data and results. Best of Luck and thanks for your vision and efforts!