pulling the knights as being mainline troops and turning them into the heavy hitters i think is great idea. splits weapon usage between the light weapon to the crawlers(boltshot,suppressor) and medium weapons to the soldiers(light rifle, scattershot, pulse grenades) and the heavy weapons to the knights(Binary Rifle, Incineration cannon, hard light blade) and watchers with their shield projection, turret spawning and knight revival abilities(no guns on them and less running away outside of map bounds please)
The mobbing of crawlers eating at your shields, keeping you out of your scope and driving you to cover. the agile soldiers weaving their way through the pack of crawlers. lobbing grenades to flush you out from cover so they can either shine light into your brain-pan or burn you to ash in the blink of an eye. with watchers flying over head catching grenades and shielding soldiers(no more crawler shielding) and if you think this force war more then enough to overwhelm you and your squad the knight commander with his cannon, his birthing of watchers and his sword glides into the fray. slower then the soldiers but with his shields far more sturdy. a one unit wrecking crew raining what amounts to hell fire into your positions. and if you can even get in close beyond his cannon's reach you now must dodge the swings and stabs of his burning sword. beware if you kill him for his watchers that guide his troops can return him from death. all during this battle you are watched from on high by a lancer(it's covered in wings why cant it fly?) waiting for one mistake to leave soot where a spartan once stood.

or just my tinfoil hat opinion