I do rely on my memory too not just colors , if you at least try to remember names you will succeed to recognize foes and friends efficiently over time unless your " special "
as far as i know NC system did more bad than good for this server.
Johny is like invisible congratulations 
I dont know if the NC system did bad for the server BUT when you come back after 2 months without playing, when everybody has build new chars (White tag), and when all the alliances have changed (half of your green tagged players are now foes and some of your "red tagged" are now friends) it's a bit hard to know if the "green guy" shooting you has "miss click" or if he's now an ennemy.
Anyway you all know that's not the time to speak about that on mumble and when the "green guy" do that a second time, you are dead and it's too late...
In that situation, the NC system could do something good, but i understand that some of you, looners, players who use to kill everybody, or players who are playing always with the same players dont worry about that.

Sadly, i dont know all the server's players and the 10 PVP chars of each player

...
It could be cool, at least, to have a command to reset you re tags...