I agree with the Beaker. Trading a strategy that can easily be replicated - and executed much faster - by computers is just going to get more and more competitive. Eventually only the players with the best equipment and the deepest pockets are going to be making money from it. Just like stock index futures arbitrage, barriers to entry will rise and profits will erode until only a handful of players are left, making a little more than the risk-free rate. Small independent arcade traders have the worst equipment, the highest execution costs, and the lowest skills & professionalism out of the remaining players, so they are going to be the first to go. Add to this the fact that the arcades have high overheads, often being based in or around expensive capital cities, and it's a recipe for disaster. As beaker says, its like the luddites vs the spinning jennies and weaving looms - the technology can do it cheaper, faster, and better than a human. That's the cold hard reality.
If there is one iron law of the markets, it is that all "free money" - leading indicators, leggable spreads, quasi-arbitrages etc - eventually disappears as competition for it increases.
Anyone trading this stuff as their main source of income, should either look to more inefficient markets (e.g. ones in developing markets), or start learning how to trade outright direction (something requiring judgement and feel, which cannot really be replicated by computers). IMO the days of intraday scalping, spreading and legging are closing fast.
I thought that post would cheer you up! I've known about apama for a while.