Actually our ship list needs renaming. LF is LF, HF should become medium fighters(and they are) while current VHF would go HF. SHF can go VHF.
Also only thing current HF need is some edits in stats, and they work. I try to fly HF class ships lately, and they seem to be good enough. (namely, grayhound and marauder) They have less agility than LF, but enough to stay on tail, a feat rather inacessible to most ships of VHF class. Also they sport more powerfull weapon arsenal than LF that gives them chance to dish out some punishment. And, since they can mount and fire torpedos (and maybe razor, not sure on it tho, i dont use it) combined with agility gives them chance to rape bomber or brick VHFs.
Reason for not using HF class mosty is that players are either not patient enough, or believe that firepower is too low.