They're obnoxious and they shouldn't last more than 30 seconds with 5 mc40s targeting one, or 5 Victory cruisers, or 5 of anything that isn't a dinky corvette. 95% of everyone's shots miss them. They soak up ungodly numbers of proton torpedoes, it's ridiculous, 20 b-wing squadrons barely dent the thing. I just fought battle after battle that it takes longer for my mid sized cruisers to destroy one ipv than it took them to destroy a Victory. This wouldn't be an issue if the enemy didn't send 15 in every fleet. Spending the first 5 mins of a battle removing ipvs before my capitals can even engage enemy capitals is causing unnecessary losses in a vain effort to save some fighters/bombers from the ipv swarm.
They should be overpowered regarding AA capability, that is their role, but the moment a heavy ship comes to bare they are toast, that is their role in a fleet, running away from more powerful enemies instead of sitting there and soaking up an entire fleet's firepower with ease.