Various friends of mine and I agree, we'd love to have an open-faced male CAST head design (Hairstyle?), and even closed-face/full helmet style Female CAST heads.
It would be something pretty interesting, as I liked the designs of other game series with cyborgs/robots with prominent helmets (Megaman X/Zero, etc.).
I do hope we get more variety for CAST heads for both genders in New Genesis, as I would love the opportunity to have an open-faced helmet on a Male CAST or a closed helmet/head on a Female CAST.