Most of the units in FAF now, are more or less balanced. However, the Tech 3 Heavy Artillery Installations are way too expensive (about the cost of about 2 Megaliths) and has too little health to justify it's costs for it's damage (and massive power needed to fire and reload). It probably takes plenty of shielding to protect it, but it will most likely be useless when (almost anything) comes close enough to destroy it? It should be one of the most devastating structures in the game, but hardly anybody would want to use it? It is certainly too costly to lose, or to even choose a good location for a Tech 3 Heavy Artillery Installation set up, for it to be useful...
The Tech 2 Artillery Installation is probably about all right, but the Tech 3 Heavy Artillery Installation is underused?