I think it could increase the value of the karma system, I am seeing a lot of downvotes that I can't explain or that I find unfair. I am also seeing excessive points on some comments.
2) Not related : if you browse someone's comments you may encounter truncated posts titles :
12 points by pg 1 hour ago | link | parent | on: Announcement: YC alumni will help us read applicat...
It would be nice to include the full title in the "title" attribute of those links.
I assume that was your intention ?
This in turn will give the few people that are very active lots of voting power.
The karma here is not so much 'quality' (though that is a component) as much as it is an odometer.