Don't you read? TWO ships...not rings...looky at the picture on hte previous page.
Attacked from the other side? Yes, that would be their main weakness...but given that anode is hte ONLY way into a system, no enemy should be there allready...anyone coming in will suffer your full wrath.
Mass fihgters and bombers can take it out? Your point being? Name me something that mass fighters and bobers can't take out? Ever heard of flak/AAAf and friendly fightercover?
IMHO, it would be best to put 90% if not ALL the turrets (anti-cap and anti-fighter) on the underside of the "rumulan-look-a-like" ships. That way you could bring 100% firepower at anything that enters the node. now give it the armament of a Colossus and do the math..
ALL of the weapons have a clear field of fire..