I've bought a couple off Race Rate over the years, and generally speaking they seemed okay, I never continued betting them myself, they just weren't my style of punting. Out of the commercially available systems they would have to be up there as perhaps some of the best (compared to some I have bought over the years anyway).

All there systems are testes live on the site, and they have shown a profit over those months otherwise they get binned. Although as we know, something that works over a few months doesn't give any guarentees to the what the future holds.

As Wesmip mentioned, really you'd be better off reading through the hundreds of pages on this site, theres quite a few systems on here that do work, and also +1 to the database suggestion, best investment I ever made!