I do not think moving after fire is too important. We do not have muzzle flash, dust-up or loud noises to give us away.
I played an attack-attack game. It was basically attack/defend, but who did what really depended on how close to whose base whoever was.
I ran my sniper rifle up a side with an assault team, and I took position near the edge of a clearing and held the position while most of the squad when back. In this field, there are basically three lanes of attack. As people would die on the other two lanes where the fighting was, the would return along the third, mine, and as soon as they left their side of the clearing, they took consistent, focused fire from my rifle.
Eventually, the other lines weakened so much they broke under my teams assault, and the next thing I knew friendlies were pouring into their side of the clearing.
Before that we were strongly on the defensive (enemies got a ten minute headstart on us because of an admin mistake). I got assigned to take out an enemy sniper and an MG, which kept coming back to the same spot. I also got me a few rifle man and an 40mm launcher.
So, an active, well placed sniper should be able to pick off man high-value, destructive targets on the enemy's attacking line in an Attack/Defend game.