The Genari Battalion Defense frigate is by far the most resilient Class IV warship, but it is still considered less popular than the Firebolt, Predator and First Honor frigates. Improvements to the hull/armor have been made, bringing it up by 7-10%.
The Sol Leningrad Type 3 Missile Destroyer has been the pariah of the Leningrad series, considered to be underpowered in offensive, even with the low power cost of the missiles. So the SIWPW-3A plasma missiles have been replaced with the significantly more advanced SIWPW-7 plasma missiles. It improves on both range and damage.