I've done an all-brett brew using Brett L as the primary yeast, followed by Brett B in the secondary. It worked fine.
My initial recipe included a healthy amount of acidulated malt, and the Brett L initially added some additional tartness as well. By the time I racked to secondary this tartness/acid character had completely changed and the beer was quite smooth.
I have since added 4 lbs of dried cherries rehydrated in a bottle of pinot noir, followed by a vial of Brett B to chew up the cherries and add more complexity. Depending on how it is tasting in a few months I may give it some time on (used) oak as well. We'll have to see on that.
Overall, though, I've been happy with the results thus far.