It might be an idea not to use exactly MA200 but something a little less or higher, because everyone else uses that, so you could be in before the MA200 traders strike and get boosted by them. I saw some tests here index crossover
If you can stomach this type of trading, not bad at all. A quick backtest showed a profit factor of about 3, avg win/avg loss of about 6.5 and around 125 points profit per share since SPY inception. max open drawdown about 3.5 points per share. Not bad at all. Longest trade lasted 2 years.