My upvotes/downvotes are worth 2 points each and my supervotes are worth 6. A person with between 10 and 100 karma on the forum has an upvote worth 1 and a supervote worth 2 (the scaling system is described in this code here I think)
My concern is that this system lends itself to groupthink, whereby the dominant views or topics are liable to get more karma, giving holders of those views more voting power, giving users that makes posts they agree with or that they see as relevant more karma, etc.
Dissenting opinions or posts not of interest to the in-group are liable to be downvoted (although karma is meant to reflect quality or relevance of a post or comment, this is of course misused), which both hides those comments but also puts off dissenting voices from commenting/posting in the future.
The justification for the current system is that people with more karma are more likely to be have better understanding and judgement, less likely to be sockpuppets or trolls and so are better positioned to vote. This is a system ported over from LessWrong (described here).
Concerns about the scaling system have been discussed on the forum previously, for example here.
Is this system more beneficial than harmful?
My silly idea is that your voting power should not scale with your karma directly, but should scale with the number of unique upvotes minus the number of unique downvotes you received. This prevents circular feedback.
Reasons
Hypothetically, if you had two factions which consistently upvote themselves, A with 67 people, and B with 33 people. People in A will have twice as many unique upvotes as people in B, and their comments can have up to 4 times more karma (in the simplistic case where voting power scales linearly with karma).
However, if voting power depends not on unique upvotes but on karma, then at first people in A will still have twice as many unique upvotes as people in B, and their comments will still have more than 4 times more karma. But then, (in the simplistic case where voting power scales linearly with karma), their comments will have 8 times more karma. Which further causes their comments to have 16 times more karma.
This doesn't happen in practice because voting power doesn't scale linearly with karma (thank goodness), but circular feedback is still partially a problem.