Oh, I'm also using Fermcap-S and it's weird stuff. Kills all the suds in the boil, but they come back when you shake the carboy to oxygenate it. Also, it didn't kill all the krausen but I bet it cut it in 1/2 or 1/3. I'm still fermenting though so I don't know how it does post-fermentation.
I've used it on two boils and it fixes the over-boil problem pretty handily though. They should call it "Suds-n-Death".