I do wonder what a goat would sound like if it were as big as a man. Most larger animals sound different to their smaller counterparts - just look at the differences between ankle-height dogs and massive dogs, domestic cats and lions/tigers/etc... markedly different. I'm not sure that supergoats would moo, but I doubt they would bleat, either. Probably some kind of deep, gruntish bleat... almost a mix between a bleat and a moo.