There are no class mods that boost this skill beyond 5 levels.
The turret obtains a visible green laser sight.
The accuracy advantage is significant but unnecessary, unless a player is in the habit of setting the turret up to fire at enemies from great distances. However, even in close range action, the nominal expenditure of a single skill point into Laser Sight is often worth it, simply to keep track of what the turret is targeting, especially to take advantage of the Slag effect if Double Up is active.
Even if the turret is destroyed, the green laser will still be visible.
If alongside this skill Double Up is active, the second gun won't have a laser sight too; unlike as shown in the Borderlands 2 Trailer.