Volatility can be a major concern with Bitcoin. Look at the exchange rates during the past 24-hours. In BTC-e, it hit $880 after going up to $1,100. Volatility of almost 20% in a single day. With gold, the maximum volatility is in the range of 2-3%.
bitcoin exchange rate stability depends only on the Exchange trading, if it is artificially regulated. A gold itself has a high value.