I agree that the Ltg is more "unreal", but if the sniper rifle was like the UC2 one, with a smoke trail and 1.6 second reload time, it could do the job just fine.
Also, if you're going to have both Ltg and sniper, there are some things you could do to keep sniper less redundant, ie 0.8 second reload time, with 100 headshot damage, but only about 20 non-headshot damage...this would make it much different than the Ltg.
Also, as far as projectile snipers, the Generations mod for Quake 3 did something cool with the Wolfenstein class sniper rifle. The fire rate was on par with the other rail guns (about 1.6 sec reload) but it was projectile, and ricocheted off of walls. There was nothing more satisfying than making precise sniper shots from around corners by leading and predicting the opponent without even seeing them...Also, the projectile glowed like a tracer, so it was still relatively visible to give away player's positions, though not as much as a rail or lightning trail.