sma seems unbelivable in backtesting. It never quite works out in real trading. Try papertrading this system before trading. With SMA crossover on a daily chart you will get clobbered. Not to mention if you try to go long/short with a SAR type of system with this approach you will NEVER find any stock to short since better informed traders that use more advanced indicators on shorter time frames are lightyears ahead of you. They are taking their profits as you are just getting the signal.
Although I don't particulary like moving averages here are our analytical thoughts on the matter. http://www.trade-ideas.com/FAQ.html#Q15
Look how much the market has gone up in the past 12 months. Of course almost every stock went up with it, no matter what the technical indicators were saying. Look at 50/125 crossUNDERS and see if that was a good bearish indicator too. I bet it isn't.