Just to humor you: Ill stop, this is all getting off topic and im contributing more to it than id like.
Well If the game is going to make sence it should be like in real life with a Helm the chance is lower for you to get a Headshot or die realy depends on the caliber of a weapon it just gives more "Protection". But since it is an MMO just for the fun they could make an option to remove Helm not sure if that would make any Diference but since all Space marines have an Helmet, cant realy tell and has Araghast said its true so i guess no you are gonna hear the damn Helmet
I'm all about wearing a helm, but it should definitely be an option to take it off. Also they should have different varieties of helms. Not just the different Mks, but variants such as the knightly looking ones too.