I think you are all missing the point.
The system isn't about "rating" anybody. Nor is ones reputation an indication of how well liked they are.
The system is a method to reward those who make contributions to the site for the benefit of others, or present information in a logical and factual manner while respecting others.
Not to mention the system won't allow somebody to continually give the same member either positive or negative karma over and over.
Lets just give it a try for a bit of time, and see how it works out before we jump to conclusions about what "might" happen before it does. If it doesn't work, we can discontinue its use.
Now rep me for a well thought out response! JK!