“Is it even possible to lift and aim a weapon with a 200-round magazine?”
According to Gun Zone, 100 rds. of 5.56 ammo weighs approximately 3.7 lbs. So 200 rds. would be 7.4 lbs. not counting the weight of the magazine and the weapon itself. So without any accoutrements, (red dot, light, and whatever else) you are looking at probably 12 lbs. for the system. Not horribly heave, but I wouldn’t want to lug it around for hours on end.
We did that with M-14s all day long when I was in the Corps. No biggie.