Check through the different time frames on this chart and you'll see there's barely a dimes worth of difference in the actual charts of IWM and IWN in the intraday moves on a % basis so my only concern would be the spread opening up and liquidity drying up when the market moves hard. I'm using options mostly in my trading lately and so I need something very liquid. If you were position trading with weeks and months or even quarters and year to accomplish your goals then it does appear the Russell Value ETF has slightly outperformed the R2K. (~5% over 2 years)