I think a simple hotkey that shows all HUD elements when pressed and then fades things back out when unpressed would be sufficient. Use that for a quick reminder of your quest and such. I think the only HUD elements that should always be on would be a minimap with compass, and groupmates icons when grouped. You don't even need an HP bar for your teammates, simply add border around their icon that changes colour from green down to red, flashing when they drop below say 20% HP. For those who are colorblind perhaps an alternate toggle that changes the opacity of the icon in a clockwork pattern, again with flashing border when they drop below 20% HP.
Oh wait, you meant the border around the team mate and not the screen.
One button to show and fade out entire hud is bad idea. I'm not the only one who want health and energy be visible at all times. ammo, armor, gauge bar fading in and out are ok for us.
Likes:
Vladplaya