i can speak only from my own experience on this.................a true game bred hen, thats bred to produce sporting cocks will generally become mean to their broods once they decide to wean them. but so will most all types of hens. only difference is, a game bred hen has the temperment, the power, the athleticism to actually kill something when she wants to. my lil OEGB will start to peck her brood when she wants to start laying again, and wean them. and these are free ranged. ive had free ranged game hens become brutal on their own young but this is not common place mainly b/c my hens that were worth breeding were all penned up. they were far to valuable to risk running lose where predators or each other would kill or wound themselves. these type hens are priceless when cocking was legal in certain venues.
now all this is also based on "individual basis" not all game hens are as bad as i speak of. some were more tolerant of their young, than others. i have two hens, full sisters. one will keep her young much longer, actually start laying, b4 weaning them, and i trust her, b/c she has proven herself. her full sister is rough, weans early and there is little to no warning. but most all game hens are as i described. that i have own, and from ones others have own.
but with all this said. there is no better brood hen, or mother hen than a game hen. they are extremely broody, waiting till they have 8-12 eggs per nest, usually wont give up a nest, will take their death from a predator protecting their clutch, and after hatching, protect thier brood, against any and all. ive seen them go after hawks before. others have said to see them fly after hawks,