There is one major problem.
If somebody gets a lot of 7/10 votes, he has fairly high karma.
If I now see a post, which is good and i rate this member a 6/10 because he had one good post, his Karma gets downed, because my rating is below the average.
It would be better to add Karma Points for every vote over 5, and to lower Karma Points for every Vote under 5.
If a member gets a 10 he'll get more points than if he gets a 6. Though he still gets points with a 6.
If I rate a member 2 or more times ( lets say from a 8 to a 6) his Karma will get lowered, due to a lower ranking than before.
I hope this is understandable. I am german...