My base is a new LVL-8 most of my things are only LVL-7 (including all my Turrets, Walls, and Shields).
They did only 12% damage... You know what got me that win? Good base design and Guard Reserves (Trooper Skins+Trooper Guards, Sniper Guards, and Wall Bracing).
Is it over powered compared to other army setups? Yes, but if you are taking care of yourself, it is not a problem.