This is fantastic. Love the clean, straightforward interface. However I have a feeling that anyone knowledgeable enough to profit from this is probably already heavily invested in another system for doing these calculations and/or feel the rules system isn't flexible enough. One thing you could do is to implement sharing. ie, have a list of "top performing strategies measured from date of creation". Then let users subscribe to other users' "proven" strategies for a fee - you take half and the author takes half - this could be an alternative way to monetize the site as well attract the kind of people who make a living doing this - ie the kind of people you want talking about your product.