Technically, when the BJCP says a unique flavor contributor "is acceptable", it shouldn't ever push the beer out of style. I think this is more often the case, especially in a style that varies in interpretation (saison, American IPA, strong ale).
If this is for a competition, I'd stay away from a blend (at least at first). You may get too much brett character, which will lead judges to believe the beer has off flavors or was crafted to have too thin mouthfeel, high carbonation, or an infection.
You can bottle up a bunch in 12 oz and drop brett in a few to try it out. If you like it, add it to your bottling bucket next time.
Actually, if you REALLY like it, the hell with the judges