warning: wall of text
As a vet player of Mortal Online, i do not agree with the reputation system of -50 = permanent killer, unless it is very difficult to get there.
When i played mortal online the worst people of the server were the "innocent" ones, they would always zerg protect the people sieging our property, there is a murdercount system similar to your reputation system.
once you hit 5 murdercounts you become a murderer, the problem was, i was a mounted archer and in a single fight where we were defending our own property, i shot 32 different people with arrows, i got 32 murdercounts and it takes 8h ingame to burn a single murdercount.
if another person was killed while "burning" murdercounts your timer would reset to 8h, and you would receive another murdercount
i tried my hardest to not be a murderer in that game, but eventually i was forced to be one protecting my own property.
if i am forced into the same thing in LIF then i will be quiting, i cannot afford to make a new char every time someone attacks my property, you need to have a clear system in place to make sure we can defend ourselves without taking on murdercounts, perhaps have a territory, where if somebody enters your territory you can kill them without consequence, if you can do this, i will be happy to pay whatever cost you put on the chars.
i have quit MO because of how much safety the "innocent" people have, i would like a system where your reputation drops if you kill a murderer or a innocent, perhaps a lower reputation drop on killing a murderer, the people of MO would attack a murderer on sight, knowing they can run to safety or call in more people knowing you cannot run to safety.
TL;DR
the reputation system could be griefed, forcing people to buy new people, or quit the game