Neat idea. I suspect that it will suffer just like comment karma does now. I think the practice of the matter for me is that dimension reduction to 1d didn't work. Other people have an opinion of text that is clearly radically different from mine. An example of something that I dislike reading is kvetching about how "corporations are ruining this and that". It's not that I disagree and don't want to see the opinion. I believe that the SNR on that is low. It's usually the 500th time I'm going to see that comment and there's rarely anything novel in it. But comments like that are popular amongst others.

So clearly opinions vary, and I'm a fan of that. The past version of social networks involved moderators who acted like the steering committee of the place and kept the culture going. But social networks like HN are very big now, and big social networks do have lots of advantages, but they come with the other side of things: I no longer have a way to select the people I want to listen to (especially on a flatspace like HN).

So I cannot rely on all other people, and I cannot rely on moderators. Realistically, an arbitrary person cannot also rely on me. But maybe some people can rely on me. And maybe there are some people I can rely on. So I'd rather treat my network as an overlay over a fundamental larger network. And I'll be missing in many people's overlay and others will be missing in mine and I like that.

But still, perhaps better 'karma' alternatives exist. If your score works, I'd be thrilled!