Lol. Cover to cover. Level 3 and above control points are ridicolous. 30 npc rushing you. Same goes for missions on challenge mode. Its not about cover. When something is unbalanced then is unbalanced. period.
Out of curiosity, a question for everyone:
How difficult do you feel the hardest content in the game should be? Solo or in a group? How much of a challenge do you feel true endgame should pose?