I enjoy flying HFs. Have Switchblade and Centurion. There are no major balance issues. But..
LFs got 850 eps regen in 4.86. How about to give HFs the same +50 eps? Also, HF cruise speed could be put somewhere between VHFs and LFs.
Could be just great.
P.S. changing fighter's thruster speed can seriously affect PvP balance in my opinion, ie chasing shieldrunning LF or HF on a VHF becomes almost pointless. Better leave this as it is.