Quote from cable:
IMHO, if you're trading a very small OTC stock with an average volume of 1000 shares traded per day, then yeah, you shouldn't let anyone else know what you're planning on doing -- until after it's done -- but if you're trading oil, coffee, IBM, or the Euro, nobody knows and nobody cares about your system even if there are thousands trading it. You're not even a drop in the bucket.
Good points, same with systems that use limit orders for entries/exits. The law of demand and supply is against you if you reveal your system as then you will have to compete with some more crowd to get a fill at your limit price. But for liquid markets this is less of an issue although not to be completely neglected if you care about the psychological comfort of not being pissed off because you did not get your fill even if the market did flirt with your entry/exit price for a while. For systems that call for entries/exits by market/stop orders this is not a problem of course, although it can give you a bigger slippage on stop orders in markets that are not very liquid.