To further elaborate on my sniper idea:
Snipers work in pairs. One spots, the other attacks.
As such in BD, I would imagine the sniper is a support unit who benefits from a unit with strong sensors.
After being spotted, the sniper would pick off units at extreme distance. With no spotter, the sniper would not be able to take full advantage of its range.
enemy units would be alerted to sniper shots regardless of cloak, but would not know "exactly" where the shot came from, allowing the sniper to relocate between shots.