Not really that much, there's been cases in the past but it wasn't removed due to users doing it this time around. Was more to please the majority of the users who is unhappy about the negative karma option. The most cases I've seen users having negative karma on the forum it's mostly because of plain out stupid or rude comments or other rule breaking of the boards, but this way a users are not able to judge other members by their negative karma.
We will try out the karma system like this for a while and see how it goes.