T4 Gear is too strong. People who grind PVP10 gear are out DPS'ed by PVEers who work a fraction of the time on their alt for the same power.
PVE Gear and PVP gear were originally intended to be for their separate purposes.
My suggestion is simple: Add negative pvp rating on all PVE items. Forcing people to use the same balanced gear for pvp, and/or balancing out PVE items to PVP gear.
(PvP gear has +PvP combat rating, magic dmg, etc. just add -PvP damage)