I would say that PSLDX has proven itself. Max drawdown since inception (2008) is about the same as VFINX, less than VTIAX/VGTSX. Return in 2008 was -33%, compared to -37% for the S&P 500. In March, it dipped more than the S&P, but not terribly so. The only year it didn't significantly outperform the S&P was 2013.