I look at robustness as more a matter of not blowing up over time. Systems that are curve-fitted or overly optimized tend to have significantly worse real time performance than their backtested results. a common way to evaluate a system for robustness is to run a sensitivity analysis of its parameters. It really shouldn't make that much difference if your moving average is 12 days or 15 or if your stochastic lookback period is 7 periods or 10.