haven't seen them yet. I'm at the 3rd mission, I didn't expect them to have guns at first (I read they are f***** dogs) and got surrounded... but I meant, their numbers make them more dangerous than knights so far.
I had trouble with the infinity holdout as well for a bit because the light rifles that the knights left behind seemed to blend into the ground really well, and I also didn't feel like running back and forth from the only spot of cover as often as I could have, but that was before I tried using the turret (farthest from the door). The earlier you get on it, the easier the holdout is. I think that the prometheans might actually be programmed to be less accurate and aggressive on that part.