This is really great work PDP.
I understand that it took you much time.
I encourage trading this with GDX as you suggested, because it will give you much confidence to trade a system that you have back-tested.
Regarding the "poor" results for IWM in 2011: 15.85%, against SPY: 22.43%.
This is not normal, as both trades are entered as the same dates.
I suspect that there is maybe a calculaton or data error somewhere for that year.
You might check the data trade by trade: you pull IWM/SPY data from the Yahoo historical site and then compare the entry/exit prices of your system for each trade. Since there are only 10 trades per year, this should be very quick.
Pascal