It's a good idea. An example of a similar concept is
www.blogabet.com. A feature I like about blogabet is that it requires users to enter odds for their picks from some website (oddsoddsodds.com or something similar). Users can't enter inflated odds for their picks and sneakily exaggerate the returns from their systems. It may be worth pointing out that a clunky, inconvenient mechanism for entering bets in a strategy imposed upon posters may actually deter people from posting their systems.
As for making Sniffy a "dynamic" tool that allows picks to be filtered by some predicate (eg how did a system perform for away picks with odds under 2.2), that's probably going to increase the level of complexity of the tool by quite a bit. The more flexibility such a tool offers in terms of the queries that users can pose, the more difficult it's going to be to implement. Not impossible (or anything near it), but storing data entered by a user, and displaying that static content on a summary web-page is a lot simpler than storing the data, and creating a "dynamic" web-page that can show the returns on systems when only bets with odds less than 2.2/2/1.8/etc. are shown. If you want this to happen soon, it's probably best to put the "dynamic" tools on the long finger, and try get the static version working first.
You could even argue that making sniffy a "dynamic" tool mightn't even be a particularly good idea. Betting systems need to be evaluated over a large number of bets in order to gauge their success. Filtering the bets posted by a poster as part of their system might return a very small set of bets. What if only 5/6 bets are returned by such a filter? If a system is filtered so that only bets where the odds are less than 1.5 are counted, and 6 bets are returned, 5 of which are winners, could it be argued that this is proof that the system is profitable for odds under 1.5? A lot of people would argue no. Since people aren't going to be posting hundreds and hundreds of picks (most wouldn't even be posting dozens and dozens) the results returned by using such filters would usually be statistically insignificant.
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