We can currently take screenshots without HUD by switching to photo mode and then taking the screenshot. However, in the heat of the battle, you don't want to remove the HUD, but you still might want to take a photo of your all out assault. It would be beneficial, in my opinion, if we could somehow take an ingame screenshot that contains no HUD with a single button. Since the 'e' key is the regular screenshot key, I propose that either shift + 'e' or ctrl + 'e' would take a screenshot without the HUD. ctrl + 'e' is probably preferable, since then we could perhaps allow screenshots while in the chat dialog (or not, if the implementation of the chat dialog doesn't make that easy).
To elaborate, "taking a screenshot without the HUD" should take a screenshot as though we had enabled photo mode, but it should not hide the HUD in the game window (only the screenshot is affected).