Here are some backtested results of some RS ETF strategies. Specific industry, asset class, and country ETFs just haven't been around long enough to really backtest for long-term out-performance, but these seem to indicate you can beat the overall market with lower drawdowns with an RS ETF strategy:
http://etfprophet.com/two-simple-relative-strength-rotation-...
http://www.bpas.com/media/HBT/dent_tactical_r3.pdf