I took a Kortul (level 5), six skirmishers, and three assailants and killed a fleet of a Kol (level 4), 12 Cobalts, and 5 LRM's...
(I only had about 500 hull at the end of it and lost all the frigates except for one assailant, but the point is, PS is extremely powerful.
Kortuls can punch through any other cap and keep going. If they hit level 6, volatile nanites destroys frigates... Eggs do have the ability to deal massive DoT's, but the armor detriment doesn't have any real effect unless you focus fire. Kortuls can devastate entire fleets, whereas Eggs can only kill one enemy at a time.