: It would be interesting to see how grunts fair in open spaces against flood
: especially armed with heavy weapons especially if grenades and needler's
: are the only effective weapons the had in the corridor fight (not to sure
: about plasma pistol) .

For Grunts on Legendary, I suspect that the plasma pistol is more effective than the needler. They have good accuracy and a high rate of fire, and obviously the shots travel faster than needles, so threats can potentially be neutralized sooner (e.g. before combat Flood get close enough to fire or melee). In the movie you can see some snappy plasma fire around 1:15 for example.