Intentionally or not you just described the karma system at fool.com (which they call recommendations). As a long time poster there it does have its uses: there are some extremely prolix boards where I skip through reading only the high rec posts, and don't have to worry about being "shielded" from controversial ideas like you get with the system here.

If i were putting someone else's karma system in here, I would put in stackexchange.com They have downvoting, but it costs the downvoter karma. So you don't get things mindlessly downvoted just because they don't kowtow. But actual low quality stuff is downvoted by high-karma individuals.

The recent improvement of showing pctage of downvotes here is nice. I think I would go the last step and "decorate" the up and down vote buttons with the total number of existing up and down votes. This would also be slightly more compact than the current system where I have points reported on top of comment, and then uninformative buttons below the post. And I would by scanning upvote totals be able to use recs in the way you want them used, if I wanted to ignore downvotes.