neither here nor there, but back in my early 'brewing' days, when I was trying to make mead, one of the books I had recommended using antifoam by just smearing a ring of the stuff around the inside of the carboy neck, so it's not in the brew and only comes in contact if the foam builds up to close to the top of the neck. don't know if that would work with fermcap but it would minimize the amount actually in the beer no?
perhaps the more stable foam of beer would not behave the same as mead foam though.