I don't know, but I have been using BCS for my last few brews and I've been very happy with the results. From BCS, I've brewed the Witbeer (HM), Kolsch (1st), Amber (2nd), Vienna, and Bock. I just entered the Vienna and Bock into competition so we'll see how those go.
The competitions are BJCP so that's what you're restricted to. I think this is a great book but your skill as a brewer is what stands out. I've made a few terrible beer from BCS when I didn't have my techniques or yeast handling down. I know it's cliche, but the beer is much more influenced by the brewer than the recipe.
That said, you should give "Designing Great Beers" by Ray Daniels a shot. It's a good book and can help you to develop your own recipes. If you're interested in making your own recipes, then it would be perfect for you. My take is that a lot of the brewing books that are out there are really targeting folks who are new to the hobby and don't have much value for me. "Designing Great Beers" is not one of those books.