U.S. small-caps have impressed this year, a fact confirmed by the 31.3% year-to-date gain for the iShares Russell 2000 ETF (NYSEArca: IWM), the largest small-cap ETF by assets. The iShares Core S&P SmallCap 600 ETF (NYSEArca: IJR) has been even better with a 34.2% 2013 pop. Small-cap ETFs with...