Actually, X-Ray, CD's will not affect cap ships (including the Kusari destroyer) unless the CD hits the bridge. So, it's best to steer the bow away from any incoming missiles, so they only hit the flanks or rear of the ship, then you can continue on cruise
Well, I only have Kusari destroyer and Large Transport for capships ATM, and if CD's disrupted the destroyer from the flanks or rear, I would never have made it into Hyperspace (but I did)! Just try to keep the nose up when you meet a hostile while in cruise :]