We could tweak the XP Lock so that it will allow xp loss if you make an attack during the current PvP Ladder. What I mean is, it would work as normal, unless you attack another player - if you do this, then your XP could be lost during PvP attacks until the ladder is next reset. How does that sound?
I have had my exp locked for a year. I don't have any problem getting even with anyone even of theirs is locked, but if others do I have no issue with removing exp locks from the game. The temporary part of it I don't like, so either remove it, or leave it as is.
If it is removed , or altered from it's original description, the fsp cost of the upgrade needs to be refunded.
Totally fine to remove it from game if it's having bad effect on pvp, and it's being manipulated.
I just haven't had any problem getting revenge myself.