I have to agree with BaconSoda that minor changes in appearance mask massive changes in performance for millitary craft. The Mrk II's are fine as they are.
As to whether ships should be geared up or down, I think we should start gearing ships down. Weapons and ships have gotten outlandishly powerful lately. I understand the need for powerful weapons to take on capital ships and such, but I think we've gone a bit overboard. Something like light fighters restricted to 7's and 8's, heavies 8's and 9's, very heavies 9's and 10's, superheavies & bombers 10's and bomber weaps. Balance the powercores to fire those weaps, rather than the current, as well as dropping the firepower of several of the weapons themselves and we are talking good stuff.
I doubt this will ever happen, to many people will scream about nerfing and it represents a massive amount of work for the devs. Still, I guy can dream.