I've heard a lot of people say it works for them, too, but I know of enough people who had the same experiences as me that I thought it was worth the warning. In my experience, the guineas just . . . well, I suppose it's just that they thought the chickens were one of the gang. Guineas have this...
The water is going to be a mess and go all over the brooder with two goslings, which could chill your other species in there. Also, brooding different species together may cause issues in adulthood if they aren't going to be kept apart from eachother as adults. Specifically, a guinea bred with...