Over the last year or so, I've farmed a lot of CS dregs into a collective culture. Not just St. Bretta, so I can't comment there from personal experience. I think some St. Bretta is truly 100% Brett, but I think that's the older stuff (maybe circa the OP). Now, I believe St. Bretta sees a primary Brett fermentation, but then it hits barrels/foeders, and so it pics up th house LAB at that point.
Anyway, I just pitched my CS culture into its first 8 gal batch. So, we'll see how that goes. As I've maintained the culture, I drink what I draw off when I re-feed, and it sours a quart quickly and nicely.
Curios to hear anyone else's experience with CS dregs.