I think if they were roos their backs be more of V shape rather then the U shape yours have. Their combs also appear to be yellow at the tops and s roo would have a vibrant red comb. The black Star has to be female, no question about that one. Maybe you just have better feed in the UK, and that can make quite a size difference, or better genes, who knows, but if speckledhen thinks they are girls...I'm on her side
Yep the combs are quite yellowey in places and definitely more pinky still than bright red. Nice to hear Wobble (black one) is a hen too although we might need to think about getting a rooster now which seems an odd idea after worrying about having four of them